Relations of psychological characteristics and team performance level in female volleyball players aged 12 to 15 years (U15)

Aim: To validate the Psychological Skills Inventory for Sport – Youth (PSIS-Y) questionnaire on a sample of youth Croatian female volleyball players, and to determine psychological characteristics of players aged 12 to 15 years, as well as possible differences according to team (competitive) performance level in variables: motivation, self-confidence, anxiety control, mental preparation, team emphasis, and concentration. Methods: The sample included 328 participants from 28 clubs competing at the national volleyball championship. We used the PSIS-Y questionnaire consisting of 44 items in 6 dimensions. Data analysis included validation of the questionnaire, descriptive parameters, and ANOVA to determine the differences in psychological dimensions between players at different performance levels, with the significance level set at P≤0.05. To determine the common effect of all the measured variables in differentiating the performance level between the groups of players, a multivariate procedure of discriminant analysis was used. Results: The participants showed a high level of motivation, medium levels of concentration, self-confidence, anxiety control, and a low level of mental preparation. According to team performance level, significant differences were found in concentration (P=0.001), anxiety control (P=0.002), mental preparation (P=0.002), and motivation (P=0.034). The applied discriminant analysis yielded two statistically significant discriminant functions: the first function (χ2=27.54; P=0.002) differentiated the group of players with the highest index of team performance level from the groups with lower indices, whereas the second function (χ2=10.39; P=0.034) differentiated the group of players with the lowest index from the three more successful groups due to higher levels of motivation and anxiety control. Conclusion: In comparison to previous findings, a decline in correlation between most psychological skills of youth female volleyball players and different levels of competitive team performance is noticed. This negative trend may be influenced by the increased importance of competition and an increased pressure put on youth players by their environment

Intra-Positional and Inter-Positional Differences Among Young Female Volleyball Players in Some Anthropological Characteristics : Doctoral Thesis

Osnovni cilj ovog istraživanja bio je utvrditi međupozicijske i unutarpozicijske razlike u nekim antropološkim obilježjima mladih odbojkašica. Uzorak ispitanika predstavljale su 204 odbojkašice mlađe kadetkinje s područja cijele Republike Hrvatske, sudionice otvorenog Državnog prvenstva u odbojci 2014. Prosječna kronološka dob ispitanica bila je 14,11±0,84 godina, indikator biološke dobi 14,12±0,76 godina, a prosječna trenažna dob 42,14±16,76 mjeseci. Skup varijabli u ovom istraživanju sastavljen je od 11 antropometrijskih mjera, 10 motoričkih testova i 3 upitnika psiholoških značajki (nada, optimizam i perfekcionizam). Od antropometrijskih mjera izmjerene su tjelesna visina, sjedeća visina, tjelesna masa, dijametar lakta, dijametar koljena, opseg nadlaktice u fleksiji, opseg potkoljenice, kožni nabor nadlaktice, kožni nabor leđa, kožni nabor trbuha i kožni nabor potkoljenice. Iz navedenih značajki naknadno su izračunati: indeks tjelesne mase, somatotip po Heath-Carter metodi te dob maksimalnog rasta u visinu (eng. Peak height velocity, PHV). Temeljem odstupanja vrijednosti PHV svakog ispitanika od prosječne PHV svih ispitanika te dodavanjem ili oduzimanjem dobivenih odstupanja od kronološke dobi, izračunat je indikator biološke dobi mladih odbojkašica. Od motoričkih testova za procjenu nespecifične agilnosti i eksplozivne snage primijenili su se testovi: koraci u stranu, 9-3-6-3-9, skok u dalj iz mjesta, bacanje medicinke iz ležanja i trčanje na 20 metara, a za procjenu specifične agilnosti i eksplozivne snage primijenili su se testovi: step hop, skok u vis iz mjesta, skok u vis nakon odbojkaškog zaleta te brzina smečirane lopte s podloge i brzina smečirane lopte preko mreže. U području psiholoških značajki, za procjenu optimizma primijenjen je Revidirani upitnik životne orijentacije (eng. Life Orientation Test – Revised), za procjenu nade Upitnik nade za djecu (eng. Children Hope Scale) i za procjenu perfekcionizma Sportski multidimenzionalni upitnik perfekcionizma (eng. Sports Multidimensional Perfectionism Scale 2). Dodatno, varijable u ovom istraživanju bile su igračka uloga i natjecateljska uspješnost. Ispitanice su podijeljene u 5 podskupina prema svojim igračkim ulogama: tehničarke, dijagonalne igračice, primačice - napadačice, srednje blokerice i libero igračice. S obzirom na plasman ekipe na natjecanju i kvalitetu pojedine igračice u ekipi odbojkašice su svrstane u dvije podskupine: manje uspješne i uspješnije. Visoke vrijednosti međučestične povezanosti i male vrijednosti koeficijenta varijacije ukazuju da sve antropometrijske varijable imaju visoku razinu relativne i apsolutne pouzdanosti. Testom za zavisne uzorke utvrđena je dobra homogenost svih antropometrijskih mjera. Svi primijenjeni testovi za procjenu motoričkih sposobnosti imaju visoku razinu apsolutne i relativne pouzdanosti. Od svih primijenjenih motoričkih testova samo test trčanje na 20 metara ima zadovoljavajuću homogenost. Kod većine ostalih testova za procjenu motoričkih sposobnosti uočen je trend poboljšanja rezultata tijekom tri izvedbe testa, vjerojatno zbog nedovoljnog broja probnih pokušaja. Kod testova za procjenu: brzina smečirane lopte s podloge i brzina smečirane lopte preko mreže radarom, primjetno je pogoršanje rezultata tijekom ponavljanja izvedbe što je vjerojatno posljedica umora zbog nedovoljne pauze između ponavljanja ili gubitka koncentracije zbog nepreciznosti u prethodnim pokušajima. Analizom metrijskih značajka psiholoških obilježja utvrđena je zadovoljavajuća pouzdanost svih ljestvica osim optimizma kod koje je zabilježena granična razina pouzdanosti. Upitnik nade, kao i ljestvice osobna očekivanja, percipirani pritisak trenera, dvojbe o kvaliteti treniranja iz upitnika za procjenu sportskog perfekcionizma imaju dobru homogenost. Upitniku za procjenu optimizma, kao i preostalim ljestvicama upitnika sportskog perfekcionizma (zabrinutost zbog grješaka, roditeljska očekivanja i ponašanja pred natjecanje) utvrđena je dobra homogenost tek nakon selekcije (odbacivanja) jedne do dvije čestice. Osjetljivost antropometrijskih, motoričkih i psiholoških varijabli procijenjena je usporedbom dobivenih vrijednosti Kolmogorov-Smirnovljevog testa s graničnim vrijednostima te dodatno analizom koeficijenata asimetrije i zaobljenosti distribucije, ako je narušen normalitet distribucije. Utvrđeno je da sve varijable osim ljestvice roditeljska očekivanja iz upitnika sportskog perfekcionizma imaju zadovoljavajuću osjetljivost. Obzirom da ta ljestvica ima daleko najniže središnje vrijednosti, što pokazuje kako mlade odbojkašice nemaju postavljena visoka očekivanja od strane njihovih roditelja, i ona je zadržana u skupu mjera za provedbu daljnjih statističkih postupaka. Diskriminacijskim analizama na cjelokupnom uzorku ispitanica neovisno o njihovim pozicijama u igri, utvrđeno je da su uspješnije odbojkašice više i teže te da su bolje u svim testovima za procjenu motoričkih sposobnosti od manje uspješnih. Nadalje, u prostoru psiholoških značajki nisu dobivene značajne razlike između manje uspješnih i uspješnijih odbojkašica, ali analizom prosječnih vrijednosti može se primijetiti da uspješnije odbojkašice imaju u apsolutnom smislu veću razinu optimizma i nade, a manju razinu sportskog perfekcionizma. Analizom prosječnih vrijednosti varijable indikator biološke dobi ispitanica uočene su međupozicijske i unutarpozicijske razlike. Libera (13,70 godina) i tehničarke (13,82 godina) su biološki najmlađe. Nešto biološki starije su dijagonalne igračice (14,17 godina) i primačice - napadačice (14,21 godina), dok su biološki najstarije srednje blokerice (14,54 godine). Unutar svih igračkih pozicija uspješnije igračice su i biološki starije. Pritom razlike u prosjeku variraju od 3 do 5 mjeseci (tehničarke, libera i primačice - napadačice), pa do spribližno godinu dana (dijagonalne igračice i srednje blokerice). Posljednično, s ciljem neutralizacije utjecaja biološke dobi na međupozicijske i unutarpozicijske razlike mladih odbojkašica, u varijablama za procjenu morfoloških značajki, motoričkih sposobnosti i psiholoških obilježja, primijenjene su analize kovarijanci s varijablom indikator biološke dobi kao kovarijatom. Kod antropometrijskih mjera indikator biološke dobi na cijelom uzorku značajno utječe na međupozicijske razlike u varijablama tjelesna visina, tjelesna masa i indeks tjelesne mase, dok na homogenijem uzorku uspješnijih odbojkašica ne utječe na međupozicijske razlike. Temeljem međupozicijskih razlika u antropometrijskim mjerama može se zaključiti da su srednje blokerice značajno više od ostalih igračkih pozicija, dok su najniže libero igračice, pa potom tehničarke. Sumarno, endomorfna komponenta somatotipa najizraženija je kod libero igračica i tehničarki, mezomorfna komponenta kod libero igračica, a ektomorfna komponenta kod dijagonalnih igračica i srednjih blokerica. Analizom međupozicijskih razlika u proporcijama pojedinih somatotipskih kategorija utvrđeno je da se primačice - napadačice ne razlikuju od tehničarki i libero igračica. Pritom libero igračice imaju značajno veću proporciju kategorije endomorfni mezomorfu usporedbi s ostalim igračkim ulogama. Srednje blokerice i dijagonalne igračice imaju značajno veću proporciju kategorije uravnoteženi ektomorfod tehničarki i libera. Na cijelom uzorku, kao i na poduzorku uspješnijih igračica, primačice - napadačice imaju značajno najbolje rezultate u većini motoričkih testova. Uspješne tehničarke i libera značajno diskriminira bolje izvođenje testova agilnosti, a u usporedbi s ostalim igračkim pozicijama imaju nešto lošije prosječne rezultate u brzini smečirane lopte. Promatrano na cijelom uzorku indikator biološke dobi značajno utječe na međupozicijske razlike u svim varijablama, dok na poduzorku uspješnijih odbojkašica, u većini varijabli. U prostoru psiholoških značajki nisu zabilježene značajne međupozicijske razlike i indikator biološke dobi kao kovarijat ne utječe na međupozicijske razlike kako na cijelom uzorku, tako i na poduzorku uspješnijih odbojkašica. Nadalje, analizom kovarijance u prostoru antropometrijskih mjera dobivena je samo jedna značajna unutarpozicijska razlika. Uspješnije tehničarke značajno su više od manje uspješnih. Nisu dobivene značajne razlike u proporcijama pojedinih somatotipskih kategorija između manje uspješnih i uspješnijih odbojkašica pojedinih igračkih uloga. Uspješnije tehničarke, primačice - napadačice i dijagonalne igračice značajno bolje su u većini testova za procjenu motoričkih sposobnosti od neuspješnih igračica na istoj poziciji. Najizraženije su razlike u testovima za procjenu brzina smečirane lopte s podloge i brzina smečirane lopte preko mreže. Na poziciji libera uspješnije igračice su značajno bolje od manje uspješnih jedino u izvedbi testa koraci u stranu, a na poziciji srednjih blokerica uspješnije igračice su bolje samo u dva testa za procjenu brzine smečirane lopte. Za promatrane igračke pozicije tehničarki i dijagonalnih igračica nisu identificirane značajne unutarpozicijske razlike u psihološkim značajkama. Uspješnije primačice - napadačice imaju manju percepciju roditeljskog očekivanja i pritiska od strane trenera od manje uspješnih igračica iste pozicije. Uspješnije srednje blokerice imaju značajno više izraženu varijablu nada, a uspješnije libero igračice imaju značajno više izražene varijable optimizam i nada te značajno manje izraženu varijablu perfekcionizam – ponašanja pred natjecanje od manje uspješnih. Na svim igračkim pozicijama indikator biološke dobi značajno utječe na unutarpozicijske razlike između manje uspješnih i uspješnijih odbojkašica u varijablama tjelesna visina i tjelesna masa. Dodatno na poziciji tehničarki, utječe na unutarpozicijske razlike u endomorfnoj komponenti, a na poziciji srednjih napadačica mezomorfnoj komponenti somatotipa. U prostoru motoričkih sposobnosti indikator biološke dobi kao kovarijat značajno utječe na unutarpozicijske razlike u većini motoričkih sposobnosti. Iznimka su tehničarke u kojima je taj utjecaj zabilježen samo u varijabli bacanje medicinke iz ležanja. U prostoru psiholoških varijabli, indikator biološke dobi utječe na unutarpozicijske razlike u varijabli ponašanja pred natjecanje kod libero igračica i srednjih blokerica, na varijablu nada kod srednjih blokerica i dijagonalnih igračica te na varijable roditeljska očekivanja i percipirani pritisak trenera kod primačica - napadačica. Dobiveni rezultati imaju veliki značaj za razumijevanje i poboljšanje procesa detekcije, identifikacije i razvoja mladih odbojkašica. S obzirom da je identificiran utjecaj indikatora biološke dobi na njihovo međupozicijsko i unutarpozicijsko razlikovanje u primijenjenim varijablama, u navedenom procesu postoji realna opasnost da se potcjene krajnje mogućnosti biološki mlađih odbojkašica. Navedene činjenice u konačnici mogu rezultirati i njihovim preranim odustajanjem od sporta.The main aim of this research was to determine inter-positional and intra-positional differences in some anthropometric characteristics of young female volleyball players. The subject sample included 204 female youth volleyball players from whole Croatia, who participated in the open Croatian volleyball championship in 2014. Mean chronological age of the subjects was 14.11±0.84 years, indicator of biological age was 14.12±0.76 years and average training experience was 42.14±16.76 months. The independent variable set in this research consisted of 11 anthropometric measures, 10 motor tests and 3 questionnaires of psychological characteristics (hope, optimism and perfectionism). The following anthropometric measures were measured: body height, sitting height, body mass, elbow diameter, knee diameter, upper arm circumference flexed, calf circumference, triceps skinfold, back skinfold, abdominal skinfold and calf skinfold. From these characteristics the following were calculated: body mass index, somatotype according to the Heath-Carter method and peak height velocity (PHV. Based on the deviations of PHV values of each subject from the average PHV value of all the subjects, and by adding or subtracting the obtained deviations from chronological age, the indicator of biological age of young female volleyball players was calculated. Among motor tests for assessing non-specific agility and explosive power, the following tests were applied: side steps, 9-3-6-3-9, standing long jump, supine medicine ball throw and 20-m sprint; and for assessing specific agility and explosive power, the following tests were applied: step hop test, standing vertical jump and spike approach volleyball jump and spiking speed from the ground and from the net. In the space of psychological characteristics, the Life Orientation Test – Revised was applied to assess optimism, the Children Hope Scale was applied to assess hope, and the Sport Multidimensional Perfectionism Scale was applied to assess perfectionism. Dependent variables in this research included player role and competitive efficacy. The subjects were divided into 5 sub-groups according to their player roles: setter, opposite hitter, passer-hitter, middle blocker and libero players. According to team placement in the competition and quality of each player in their team, volleyball players were divided into two groups: more efficient and less efficient. High values of inter-item correlation and low values of coefficients of variation indicate that all the anthropometric variables have a high level of relative and absolute reliability. Good homogeneity of all the anthropometric measures was determined by the dependent samples T test. All the applied tests for assessing motor abilities have a high level of absolute and relative reliability. Out of the motor tests applied, only the 20-m sprint test has satisfactory homogeneity. In most other tests for assessing motor abilities a trend of result improvement during the three performances of the test was noticed, probably due to the insufficient number of trials. In tests assessing spiking speed from the ground and from the net by radar, a deterioration of results was noticeable during the repeated performance, which is probably the consequence of fatigue due to insufficient rest periods between repetitions, or loss of concentration due to imprecision in previous attempts. By analysing the metric characteristics of psychological characteristics, satisfactory reliability of all the scales was determined, except optimism which showed a limit level of reliability. The hope questionnaire, as well as the scales of personal standards, perceived coach pressure and doubts about actions from the questionnaire assessing sport perfectionism have good homogeneity. The questionnaire assessing optimism, alike the rest of the scales of the Sport Multidimensional Perfectionism Scale (concern over mistakes, perceived parental pressure and organization), showed good homogeneity only after selecting (excluding) one to two items. The sensibility of anthropometric, motor and psychological variables was assessed by comparing the obtained values of the Kolmogorov-Smirnov test with the limit values, and additionally by analysing the coefficients of distribution Skewness and Kurtosis if the KS test values were above the critical value. It was determined that sensitivity of all the scales except perceived parental pressure from the sport perfectionism questionnaire is satisfactory. Given that this scale had by far the lowest means, which indicates that the subjects – young female volleyball players do not have high expectations set by their parents, it too was kept in the set of measures for further application of statistical procedures. By discriminant analyses on the overall subject sample (regardless of position), it was determined that more efficient volleyball players are taller and heavier, and did better in all the tests assessing motor abilities in comparison to less efficient players. Even though discriminant analysis in the space of psychological characteristics did not find significant differences between more efficient and less efficient volleyball players, by analysing the mean values it can be noticed that more efficient volleyball players have a higher level of optimism and hope, and a lower level of sport perfectionism. By analysing the means of subjects’ biological age, inter-positional and intra-positional differences were found. Liberos (13.70 years) and setters (13.82 years) are biologically the youngest. Opposite hitters (14.17 years) and passer-hitters (14.21 years) are somewhat biologically older. Middle blockers are biologically the oldest (14.54 years). More efficient players at all positions are also biologically the oldest. These differences range from averagely 3-5 months (setters, liberos and passer-hitters) to almost a year (opposite hitters and middle blockers). To neutralise the influence of biological age on inter-positional and intrapositional differences of young female volleyball players in the variables assessing morphological characteristics, motor abilities and psychological characteristics, analyses of covariance are applied with the indicator of biological age variable as covariate. Based on inter-positional differences in anthropometric measures it can be inferred that middle blockers are significantly taller than the other player positions, whereas libero players are the shortest, followed by setters. Liberos and setters are the most endomorphic, liberos are the most mesomorphic, and opposite hitters and middle blockers are the most ectomorphic. By analysing the inter-positional differences in proportions of separate somatotype categories it was determined that passer-hitters do not differ from setters and liberos. Libero players have a significantly higher proportion of the endomorphicmesomorph category in comparison to other player roles. Middle blockers and opposite hitters have a significantly higher proportion of the balanced ectomorph category than setters and liberos. In the overall sample, as well as the subsample of more efficient players, passer-hitters have the best results in most motor tests. Efficient setters and liberos are characterized by good performance of agility tests, and compared to the other player positions they have somewhat lower average results in spiking speed. There are no inter-positional differences in psychological characteristics. Among the anthropometric measures, the indicator of biological age significantly affects the inter-positional differences in height, body mass and body mass index in the overall sample, whereas in a more homogenous sample of more efficient volleyball players it does not affect the inter-positional differences. In the overall sample the indicator of biological age affects inter-positional differences in all the variables, and in the subsample of more efficient volleyball players in most variables. In the space of psychological characteristics the indicator of biological age does not affect inter-positional differences neither in the overall sample nor in the subsample of more efficient players. By analysis of covariance in the space of anthropometric measures only one significant intrapositional difference is found. More efficient setters are significantly taller than less efficient ones. There are no significant differences in proportions of separate somatotype categories between more efficient and less efficient female volleyball players with different player roles. More efficient setters, passer-hitters and opposite hitters did better in most tests assessing motor abilities in comparison to less efficient players at the same position. The differences are most prominent in tests assessing spiking speed. At libero position, more efficient players are significantly better than less efficient players only in the performance of side steps, and at middle blocker position, more efficient players are better only in the two tests assessing spiking speed. There are no significant intra-positional differences in psychological characteristics found for player positions of setters and opposite hitters. More efficient passer-hitters have a lower perception of parental expectations and coach pressure than less efficient players at the same position. The hope variable is significantly higher in more efficient middle blockers, and optimism and hope variables are significantly more expressed in more efficient libero players, whereas their perfectionism – organization variable is significantly less expressed than in less efficient liberos. In all player positions the indicator of biological age significantly affects intra-positional differences in body height and body mass between more efficient and less efficient female volleyball players. Additionally, it affects intra-positional differences in the endomorph somatotype component in setter position, whereas it affects the mesomorph somatotype component in middle blockers. In the motor abilities space the indicator of biological age as covariate significantly affects the intra-positional differences in most of the motor abilities. The setters are the exception as this effect is found only in the supine medicine ball throw variable. In the psychological variables space the indicator of biological age affects intrapositional differences in the organization variable in liberos and middle blockers, the hope variable in middle blockers and opposite hitters, and perceived parental pressure and perceived coach pressure variables in passer-hitters. The obtained results have great importance for understanding and improvin

Intra-Positional and Inter-Positional Differences Among Young Female Volleyball Players in Some Anthropological Characteristics : Doctoral Thesis

Osnovni cilj ovog istraživanja bio je utvrditi međupozicijske i unutarpozicijske razlike u nekim antropološkim obilježjima mladih odbojkašica. Uzorak ispitanika predstavljale su 204 odbojkašice mlađe kadetkinje s područja cijele Republike Hrvatske, sudionice otvorenog Državnog prvenstva u odbojci 2014. Prosječna kronološka dob ispitanica bila je 14,11±0,84 godina, indikator biološke dobi 14,12±0,76 godina, a prosječna trenažna dob 42,14±16,76 mjeseci. Skup varijabli u ovom istraživanju sastavljen je od 11 antropometrijskih mjera, 10 motoričkih testova i 3 upitnika psiholoških značajki (nada, optimizam i perfekcionizam). Od antropometrijskih mjera izmjerene su tjelesna visina, sjedeća visina, tjelesna masa, dijametar lakta, dijametar koljena, opseg nadlaktice u fleksiji, opseg potkoljenice, kožni nabor nadlaktice, kožni nabor leđa, kožni nabor trbuha i kožni nabor potkoljenice. Iz navedenih značajki naknadno su izračunati: indeks tjelesne mase, somatotip po Heath-Carter metodi te dob maksimalnog rasta u visinu (eng. Peak height velocity, PHV). Temeljem odstupanja vrijednosti PHV svakog ispitanika od prosječne PHV svih ispitanika te dodavanjem ili oduzimanjem dobivenih odstupanja od kronološke dobi, izračunat je indikator biološke dobi mladih odbojkašica. Od motoričkih testova za procjenu nespecifične agilnosti i eksplozivne snage primijenili su se testovi: koraci u stranu, 9-3-6-3-9, skok u dalj iz mjesta, bacanje medicinke iz ležanja i trčanje na 20 metara, a za procjenu specifične agilnosti i eksplozivne snage primijenili su se testovi: step hop, skok u vis iz mjesta, skok u vis nakon odbojkaškog zaleta te brzina smečirane lopte s podloge i brzina smečirane lopte preko mreže. U području psiholoških značajki, za procjenu optimizma primijenjen je Revidirani upitnik životne orijentacije (eng. Life Orientation Test – Revised), za procjenu nade Upitnik nade za djecu (eng. Children Hope Scale) i za procjenu perfekcionizma Sportski multidimenzionalni upitnik perfekcionizma (eng. Sports Multidimensional Perfectionism Scale 2). Dodatno, varijable u ovom istraživanju bile su igračka uloga i natjecateljska uspješnost. Ispitanice su podijeljene u 5 podskupina prema svojim igračkim ulogama: tehničarke, dijagonalne igračice, primačice - napadačice, srednje blokerice i libero igračice. S obzirom na plasman ekipe na natjecanju i kvalitetu pojedine igračice u ekipi odbojkašice su svrstane u dvije podskupine: manje uspješne i uspješnije. Visoke vrijednosti međučestične povezanosti i male vrijednosti koeficijenta varijacije ukazuju da sve antropometrijske varijable imaju visoku razinu relativne i apsolutne pouzdanosti. Testom za zavisne uzorke utvrđena je dobra homogenost svih antropometrijskih mjera. Svi primijenjeni testovi za procjenu motoričkih sposobnosti imaju visoku razinu apsolutne i relativne pouzdanosti. Od svih primijenjenih motoričkih testova samo test trčanje na 20 metara ima zadovoljavajuću homogenost. Kod većine ostalih testova za procjenu motoričkih sposobnosti uočen je trend poboljšanja rezultata tijekom tri izvedbe testa, vjerojatno zbog nedovoljnog broja probnih pokušaja. Kod testova za procjenu: brzina smečirane lopte s podloge i brzina smečirane lopte preko mreže radarom, primjetno je pogoršanje rezultata tijekom ponavljanja izvedbe što je vjerojatno posljedica umora zbog nedovoljne pauze između ponavljanja ili gubitka koncentracije zbog nepreciznosti u prethodnim pokušajima. Analizom metrijskih značajka psiholoških obilježja utvrđena je zadovoljavajuća pouzdanost svih ljestvica osim optimizma kod koje je zabilježena granična razina pouzdanosti. Upitnik nade, kao i ljestvice osobna očekivanja, percipirani pritisak trenera, dvojbe o kvaliteti treniranja iz upitnika za procjenu sportskog perfekcionizma imaju dobru homogenost. Upitniku za procjenu optimizma, kao i preostalim ljestvicama upitnika sportskog perfekcionizma (zabrinutost zbog grješaka, roditeljska očekivanja i ponašanja pred natjecanje) utvrđena je dobra homogenost tek nakon selekcije (odbacivanja) jedne do dvije čestice. Osjetljivost antropometrijskih, motoričkih i psiholoških varijabli procijenjena je usporedbom dobivenih vrijednosti Kolmogorov-Smirnovljevog testa s graničnim vrijednostima te dodatno analizom koeficijenata asimetrije i zaobljenosti distribucije, ako je narušen normalitet distribucije. Utvrđeno je da sve varijable osim ljestvice roditeljska očekivanja iz upitnika sportskog perfekcionizma imaju zadovoljavajuću osjetljivost. Obzirom da ta ljestvica ima daleko najniže središnje vrijednosti, što pokazuje kako mlade odbojkašice nemaju postavljena visoka očekivanja od strane njihovih roditelja, i ona je zadržana u skupu mjera za provedbu daljnjih statističkih postupaka. Diskriminacijskim analizama na cjelokupnom uzorku ispitanica neovisno o njihovim pozicijama u igri, utvrđeno je da su uspješnije odbojkašice više i teže te da su bolje u svim testovima za procjenu motoričkih sposobnosti od manje uspješnih. Nadalje, u prostoru psiholoških značajki nisu dobivene značajne razlike između manje uspješnih i uspješnijih odbojkašica, ali analizom prosječnih vrijednosti može se primijetiti da uspješnije odbojkašice imaju u apsolutnom smislu veću razinu optimizma i nade, a manju razinu sportskog perfekcionizma. Analizom prosječnih vrijednosti varijable indikator biološke dobi ispitanica uočene su međupozicijske i unutarpozicijske razlike. Libera (13,70 godina) i tehničarke (13,82 godina) su biološki najmlađe. Nešto biološki starije su dijagonalne igračice (14,17 godina) i primačice - napadačice (14,21 godina), dok su biološki najstarije srednje blokerice (14,54 godine). Unutar svih igračkih pozicija uspješnije igračice su i biološki starije. Pritom razlike u prosjeku variraju od 3 do 5 mjeseci (tehničarke, libera i primačice - napadačice), pa do spribližno godinu dana (dijagonalne igračice i srednje blokerice). Posljednično, s ciljem neutralizacije utjecaja biološke dobi na međupozicijske i unutarpozicijske razlike mladih odbojkašica, u varijablama za procjenu morfoloških značajki, motoričkih sposobnosti i psiholoških obilježja, primijenjene su analize kovarijanci s varijablom indikator biološke dobi kao kovarijatom. Kod antropometrijskih mjera indikator biološke dobi na cijelom uzorku značajno utječe na međupozicijske razlike u varijablama tjelesna visina, tjelesna masa i indeks tjelesne mase, dok na homogenijem uzorku uspješnijih odbojkašica ne utječe na međupozicijske razlike. Temeljem međupozicijskih razlika u antropometrijskim mjerama može se zaključiti da su srednje blokerice značajno više od ostalih igračkih pozicija, dok su najniže libero igračice, pa potom tehničarke. Sumarno, endomorfna komponenta somatotipa najizraženija je kod libero igračica i tehničarki, mezomorfna komponenta kod libero igračica, a ektomorfna komponenta kod dijagonalnih igračica i srednjih blokerica. Analizom međupozicijskih razlika u proporcijama pojedinih somatotipskih kategorija utvrđeno je da se primačice - napadačice ne razlikuju od tehničarki i libero igračica. Pritom libero igračice imaju značajno veću proporciju kategorije endomorfni mezomorfu usporedbi s ostalim igračkim ulogama. Srednje blokerice i dijagonalne igračice imaju značajno veću proporciju kategorije uravnoteženi ektomorfod tehničarki i libera. Na cijelom uzorku, kao i na poduzorku uspješnijih igračica, primačice - napadačice imaju značajno najbolje rezultate u većini motoričkih testova. Uspješne tehničarke i libera značajno diskriminira bolje izvođenje testova agilnosti, a u usporedbi s ostalim igračkim pozicijama imaju nešto lošije prosječne rezultate u brzini smečirane lopte. Promatrano na cijelom uzorku indikator biološke dobi značajno utječe na međupozicijske razlike u svim varijablama, dok na poduzorku uspješnijih odbojkašica, u većini varijabli. U prostoru psiholoških značajki nisu zabilježene značajne međupozicijske razlike i indikator biološke dobi kao kovarijat ne utječe na međupozicijske razlike kako na cijelom uzorku, tako i na poduzorku uspješnijih odbojkašica. Nadalje, analizom kovarijance u prostoru antropometrijskih mjera dobivena je samo jedna značajna unutarpozicijska razlika. Uspješnije tehničarke značajno su više od manje uspješnih. Nisu dobivene značajne razlike u proporcijama pojedinih somatotipskih kategorija između manje uspješnih i uspješnijih odbojkašica pojedinih igračkih uloga. Uspješnije tehničarke, primačice - napadačice i dijagonalne igračice značajno bolje su u većini testova za procjenu motoričkih sposobnosti od neuspješnih igračica na istoj poziciji. Najizraženije su razlike u testovima za procjenu brzina smečirane lopte s podloge i brzina smečirane lopte preko mreže. Na poziciji libera uspješnije igračice su značajno bolje od manje uspješnih jedino u izvedbi testa koraci u stranu, a na poziciji srednjih blokerica uspješnije igračice su bolje samo u dva testa za procjenu brzine smečirane lopte. Za promatrane igračke pozicije tehničarki i dijagonalnih igračica nisu identificirane značajne unutarpozicijske razlike u psihološkim značajkama. Uspješnije primačice - napadačice imaju manju percepciju roditeljskog očekivanja i pritiska od strane trenera od manje uspješnih igračica iste pozicije. Uspješnije srednje blokerice imaju značajno više izraženu varijablu nada, a uspješnije libero igračice imaju značajno više izražene varijable optimizam i nada te značajno manje izraženu varijablu perfekcionizam – ponašanja pred natjecanje od manje uspješnih. Na svim igračkim pozicijama indikator biološke dobi značajno utječe na unutarpozicijske razlike između manje uspješnih i uspješnijih odbojkašica u varijablama tjelesna visina i tjelesna masa. Dodatno na poziciji tehničarki, utječe na unutarpozicijske razlike u endomorfnoj komponenti, a na poziciji srednjih napadačica mezomorfnoj komponenti somatotipa. U prostoru motoričkih sposobnosti indikator biološke dobi kao kovarijat značajno utječe na unutarpozicijske razlike u većini motoričkih sposobnosti. Iznimka su tehničarke u kojima je taj utjecaj zabilježen samo u varijabli bacanje medicinke iz ležanja. U prostoru psiholoških varijabli, indikator biološke dobi utječe na unutarpozicijske razlike u varijabli ponašanja pred natjecanje kod libero igračica i srednjih blokerica, na varijablu nada kod srednjih blokerica i dijagonalnih igračica te na varijable roditeljska očekivanja i percipirani pritisak trenera kod primačica - napadačica. Dobiveni rezultati imaju veliki značaj za razumijevanje i poboljšanje procesa detekcije, identifikacije i razvoja mladih odbojkašica. S obzirom da je identificiran utjecaj indikatora biološke dobi na njihovo međupozicijsko i unutarpozicijsko razlikovanje u primijenjenim varijablama, u navedenom procesu postoji realna opasnost da se potcjene krajnje mogućnosti biološki mlađih odbojkašica. Navedene činjenice u konačnici mogu rezultirati i njihovim preranim odustajanjem od sporta.The main aim of this research was to determine inter-positional and intra-positional differences in some anthropometric characteristics of young female volleyball players. The subject sample included 204 female youth volleyball players from whole Croatia, who participated in the open Croatian volleyball championship in 2014. Mean chronological age of the subjects was 14.11±0.84 years, indicator of biological age was 14.12±0.76 years and average training experience was 42.14±16.76 months. The independent variable set in this research consisted of 11 anthropometric measures, 10 motor tests and 3 questionnaires of psychological characteristics (hope, optimism and perfectionism). The following anthropometric measures were measured: body height, sitting height, body mass, elbow diameter, knee diameter, upper arm circumference flexed, calf circumference, triceps skinfold, back skinfold, abdominal skinfold and calf skinfold. From these characteristics the following were calculated: body mass index, somatotype according to the Heath-Carter method and peak height velocity (PHV. Based on the deviations of PHV values of each subject from the average PHV value of all the subjects, and by adding or subtracting the obtained deviations from chronological age, the indicator of biological age of young female volleyball players was calculated. Among motor tests for assessing non-specific agility and explosive power, the following tests were applied: side steps, 9-3-6-3-9, standing long jump, supine medicine ball throw and 20-m sprint; and for assessing specific agility and explosive power, the following tests were applied: step hop test, standing vertical jump and spike approach volleyball jump and spiking speed from the ground and from the net. In the space of psychological characteristics, the Life Orientation Test – Revised was applied to assess optimism, the Children Hope Scale was applied to assess hope, and the Sport Multidimensional Perfectionism Scale was applied to assess perfectionism. Dependent variables in this research included player role and competitive efficacy. The subjects were divided into 5 sub-groups according to their player roles: setter, opposite hitter, passer-hitter, middle blocker and libero players. According to team placement in the competition and quality of each player in their team, volleyball players were divided into two groups: more efficient and less efficient. High values of inter-item correlation and low values of coefficients of variation indicate that all the anthropometric variables have a high level of relative and absolute reliability. Good homogeneity of all the anthropometric measures was determined by the dependent samples T test. All the applied tests for assessing motor abilities have a high level of absolute and relative reliability. Out of the motor tests applied, only the 20-m sprint test has satisfactory homogeneity. In most other tests for assessing motor abilities a trend of result improvement during the three performances of the test was noticed, probably due to the insufficient number of trials. In tests assessing spiking speed from the ground and from the net by radar, a deterioration of results was noticeable during the repeated performance, which is probably the consequence of fatigue due to insufficient rest periods between repetitions, or loss of concentration due to imprecision in previous attempts. By analysing the metric characteristics of psychological characteristics, satisfactory reliability of all the scales was determined, except optimism which showed a limit level of reliability. The hope questionnaire, as well as the scales of personal standards, perceived coach pressure and doubts about actions from the questionnaire assessing sport perfectionism have good homogeneity. The questionnaire assessing optimism, alike the rest of the scales of the Sport Multidimensional Perfectionism Scale (concern over mistakes, perceived parental pressure and organization), showed good homogeneity only after selecting (excluding) one to two items. The sensibility of anthropometric, motor and psychological variables was assessed by comparing the obtained values of the Kolmogorov-Smirnov test with the limit values, and additionally by analysing the coefficients of distribution Skewness and Kurtosis if the KS test values were above the critical value. It was determined that sensitivity of all the scales except perceived parental pressure from the sport perfectionism questionnaire is satisfactory. Given that this scale had by far the lowest means, which indicates that the subjects – young female volleyball players do not have high expectations set by their parents, it too was kept in the set of measures for further application of statistical procedures. By discriminant analyses on the overall subject sample (regardless of position), it was determined that more efficient volleyball players are taller and heavier, and did better in all the tests assessing motor abilities in comparison to less efficient players. Even though discriminant analysis in the space of psychological characteristics did not find significant differences between more efficient and less efficient volleyball players, by analysing the mean values it can be noticed that more efficient volleyball players have a higher level of optimism and hope, and a lower level of sport perfectionism. By analysing the means of subjects’ biological age, inter-positional and intra-positional differences were found. Liberos (13.70 years) and setters (13.82 years) are biologically the youngest. Opposite hitters (14.17 years) and passer-hitters (14.21 years) are somewhat biologically older. Middle blockers are biologically the oldest (14.54 years). More efficient players at all positions are also biologically the oldest. These differences range from averagely 3-5 months (setters, liberos and passer-hitters) to almost a year (opposite hitters and middle blockers). To neutralise the influence of biological age on inter-positional and intrapositional differences of young female volleyball players in the variables assessing morphological characteristics, motor abilities and psychological characteristics, analyses of covariance are applied with the indicator of biological age variable as covariate. Based on inter-positional differences in anthropometric measures it can be inferred that middle blockers are significantly taller than the other player positions, whereas libero players are the shortest, followed by setters. Liberos and setters are the most endomorphic, liberos are the most mesomorphic, and opposite hitters and middle blockers are the most ectomorphic. By analysing the inter-positional differences in proportions of separate somatotype categories it was determined that passer-hitters do not differ from setters and liberos. Libero players have a significantly higher proportion of the endomorphicmesomorph category in comparison to other player roles. Middle blockers and opposite hitters have a significantly higher proportion of the balanced ectomorph category than setters and liberos. In the overall sample, as well as the subsample of more efficient players, passer-hitters have the best results in most motor tests. Efficient setters and liberos are characterized by good performance of agility tests, and compared to the other player positions they have somewhat lower average results in spiking speed. There are no inter-positional differences in psychological characteristics. Among the anthropometric measures, the indicator of biological age significantly affects the inter-positional differences in height, body mass and body mass index in the overall sample, whereas in a more homogenous sample of more efficient volleyball players it does not affect the inter-positional differences. In the overall sample the indicator of biological age affects inter-positional differences in all the variables, and in the subsample of more efficient volleyball players in most variables. In the space of psychological characteristics the indicator of biological age does not affect inter-positional differences neither in the overall sample nor in the subsample of more efficient players. By analysis of covariance in the space of anthropometric measures only one significant intrapositional difference is found. More efficient setters are significantly taller than less efficient ones. There are no significant differences in proportions of separate somatotype categories between more efficient and less efficient female volleyball players with different player roles. More efficient setters, passer-hitters and opposite hitters did better in most tests assessing motor abilities in comparison to less efficient players at the same position. The differences are most prominent in tests assessing spiking speed. At libero position, more efficient players are significantly better than less efficient players only in the performance of side steps, and at middle blocker position, more efficient players are better only in the two tests assessing spiking speed. There are no significant intra-positional differences in psychological characteristics found for player positions of setters and opposite hitters. More efficient passer-hitters have a lower perception of parental expectations and coach pressure than less efficient players at the same position. The hope variable is significantly higher in more efficient middle blockers, and optimism and hope variables are significantly more expressed in more efficient libero players, whereas their perfectionism – organization variable is significantly less expressed than in less efficient liberos. In all player positions the indicator of biological age significantly affects intra-positional differences in body height and body mass between more efficient and less efficient female volleyball players. Additionally, it affects intra-positional differences in the endomorph somatotype component in setter position, whereas it affects the mesomorph somatotype component in middle blockers. In the motor abilities space the indicator of biological age as covariate significantly affects the intra-positional differences in most of the motor abilities. The setters are the exception as this effect is found only in the supine medicine ball throw variable. In the psychological variables space the indicator of biological age affects intrapositional differences in the organization variable in liberos and middle blockers, the hope variable in middle blockers and opposite hitters, and perceived parental pressure and perceived coach pressure variables in passer-hitters. The obtained results have great importance for understanding and improvin

Identification af Explosive Power Factors as Predictors of Player Quality in Young Female Volleyball Players

With the purpose of determining the factor structure of explosive power, as well as the influence of each factor on situational efficiency, 56 young female volleyball players were tested using 14 tests for assessing nonspecific and specific explosive power. By factor analysis, 4 significant factors were isolated which explained the total of over 80% of the common variability in young female volleyball players. The first factor was defined as volleyball-specific jumping, the second factor as nonspecific jumping and sprinting, the third factor as throwing explosive power, while the fourth factor was interpreted as volleyball-specific throwing and spiking speed from the ground. Results obtained by regression analysis in the latent space of explosive power indicate that the identified factors are good predictors of player quality in young female volleyball players. The fourth factor defined as throwing and spiking speed from the ground had the largest influence on player quality, followed by volleyball-specific jumping and nonspecific jumping and sprinting, and to a much lesser extent, by throwing explosive power. The results obtained in this age group bring to the fore the ability of spiking and serving a ball of high speed, which hinders the opponents from playing those balls in serve reception and field defence. This ability, combined with a high standing vertical jump reach and spike approach vertical jump reach (which is the basis of the 1st varimax factor) enables successful performance of all volleyball elements by which points are won in complex 1 (spike) and complex 2 (serve and block). Even though the 2nd factor (nonspecific jumping and sprinting) has a slightly smaller impact on situational efficiency in young players, this ability provides preconditions i.e. preparation for successful realisation of all volleyball elements, so greater attention must be paid to perfecting it in young female volleyball players

Biomotor Status and Kinesiological Education of Students Aged 13 to 15 Years – Example: Karate

The aim of this paper was to obtain information relevant for efficient selection in karate, based on comparison of biomotor status of male/female7th and 8th grade students in primary school »Bija}i« from Ka{tel Novi and karate practitioners and non-practitioners (cadets) in Croatia. For this purpose, a sample was drawn of 352 primary school students (150 males and 152 females) and 50 karate practitioners (25 males and 25 females), all aged 13 to 15 years, and 2 morphological measures (body height and body mass) and a battery of 6 motor tests was used. A biomotor system which determines the situation efficacy in male and female karate practitioners was defined based on the comparison of test results of students from Ka{tela, Croatian karateka and Croatian standards, factor analysis of applied variables and discriminant analysis of those variables between karate athletes and students from Ka{tela. In male karate athletes, general motor efficacy in karate is based on explosive strength of jumping type, repetitive strength of the trunk and coordination, followed by flexibility, static strength of the arms, and movement frequency speed. In female karate athletes, integration of force, coordination, muscle tone regulation and speed is dominant for achieving success in karate. Female karate athletes use speed and fine muscle tone regulation in motor functioning more than male karate athletes, who use basic strength more

Biomotor Status and Kinesiological Education of Students Aged 13 to 15 Years – Example: Karate

The aim of this paper was to obtain information relevant for efficient selection in karate, based on comparison of biomotor status of male/female7th and 8th grade students in primary school »Bija}i« from Ka{tel Novi and karate practitioners and non-practitioners (cadets) in Croatia. For this purpose, a sample was drawn of 352 primary school students (150 males and 152 females) and 50 karate practitioners (25 males and 25 females), all aged 13 to 15 years, and 2 morphological measures (body height and body mass) and a battery of 6 motor tests was used. A biomotor system which determines the situation efficacy in male and female karate practitioners was defined based on the comparison of test results of students from Ka{tela, Croatian karateka and Croatian standards, factor analysis of applied variables and discriminant analysis of those variables between karate athletes and students from Ka{tela. In male karate athletes, general motor efficacy in karate is based on explosive strength of jumping type, repetitive strength of the trunk and coordination, followed by flexibility, static strength of the arms, and movement frequency speed. In female karate athletes, integration of force, coordination, muscle tone regulation and speed is dominant for achieving success in karate. Female karate athletes use speed and fine muscle tone regulation in motor functioning more than male karate athletes, who use basic strength more

Uticaj elektronske komunikacije na virtuelne organizacije

U radu se istražuju načini uspostavljanja komunikacija u virtuelnim organizacijama. Autori zaključuju da uprkos novim tehnologijama kao važnom aspektu funkcionisanja virtuelnih organizacija, još uvek ljudski faktor ima presudan uticaj na obavljanje njihovih aktivnosti. Takođe, posebno je istaknuto da se s razvojem novih tehnologija, mogu i u budućnosti očekivati radikalne promene u načinima komunikacije u virtuelnim organizacijama. Medjutim, po mišljenju autora, nije lako unapred predvideti smer u kojem će te promene biti orijentisane. Ono što je sigurno predvidivo, jeste činjenica da će one zavisiti ne samo od tehnoloških promena, već i od promena u svesti zaposlenih u virtuelnim organizacijama

Study on the dependence of the critical temperature Tc on pressure in YBa2Cu3O6+x

In the present study experimental data available in the literature have been employed to investigate behavior of the critical temperature Tc as a function of the pressure P, in the YBa2Cu3O6+x high temperature superconductor (HTSC). We estimated the maximal critical temperature Tc,max(P) which can be achieved in this material under pressure applied at temperatures low enough to prevent oxygen reordering. We found that it approximately equals to 114K corresponding to x ≈ 0.77

Impact of oxygen disorder on Tc supression in Zn dopedreba2Cu3O6+x superocnductors

Conducting properties of REBa2Cu3O6+x(RE123) type high Tc superconductors (RE=Y, 4f elements) are highly sensitive to the oxygen order in the oxygen deficient CuOx planes which can be disrupted by doping with different metals,thus leading to a change of the superconducting transition temperature Tc. In this article we shall employ a simple theoretical model of charge transfer to studyhow Tc(x) dependence is affected by the increase of oxygen disorder in the CuOx planes, which is displayed in reduced average CuO chain length, lav. The results indicate that though the increased oxygen disorder can produce significant decrease in Tc, it cannot be the only factor responsible forTc reduction in Zn doped RE123 superconductors

Ekonomski uticaj ulaganja u proizvode sa dodatom vrednošću

Stone fruit plantations constitute more than two-thirds of all fruit plantations in Serbia (approximating to 67%), whereas plum plantations account for two-thirds of all stone fruit plantations in the country. Stone fruit production is commonplace in all parts of Serbia. There are large areas of extensive fruit plantations in Western Serbia and Šumadija (Valjevo, Kraljevo, Užice, Bajina Bašta and Kragujevac), whereas the largest fruit plantation areas are in the municipalities of Grocka, Smederevo, Prokuplje, Topola and Valjevo. Plum plantations are estimated to claim the biggest share of extensive fruit plantations in Serbia. A value chain is a powerful tool for increasing the added value of products. It represents a synthesis of activities carried out by a business organization in order to produce, pack, design, market, deliver and support its products. In the production of dried plums with stones, with an average production of 112 kg/day and an average selling price of 350 RSD/kg, the realized profit amounted to 18,237 RSD/day (for 24 hours of drying). With an average drying ratio of 4:1 (100 kg of fresh plums yield 25 kg of dried plums with a moisture content of 26 %), the added value of dried plums is increased approximately 6 times compared to fresh plums. According to the economic indicators calculated in the organic production of plums, a positive financial result (profit) of 3.940 €/ha was achieved. The cost price of plum production was 0.16 €/kg, and the selling price was 0.38€/kg. As the organic production of plums generates profit and the cost price per unit of measure is significantly lower than the purchase price of plums (0.16 €/kg lt 0.38 €/kg), the organic production of plums is economically justified for the producer.Preko dve trećine zasada voća u Srbiji čine koštičave voćne vrste (oko 67%), a u okviru toga, dve trećine otpada na šljivu. Proizvodnja koštičavih voćnih vrsta je zastupljena u svim delovima Srbije. U Zapadnoj Srbiji i Šumadiji se nalaze veće površine ekstenzivnih zasada (Valjevo, Kraljevo, Užice, Bajina Bašta, Kragujevac), a najveće površine pod plantažnim zasadima su u opštinama Grocka, Smederevo, Prokuplje, Topola i Valjevo. Procenjuje se da najveći udeo ekstenzivnih zasada u Srbiji čine zasadi šljive. Lanac vrednosti predstavlja snažan instrument za pronalaženje načina za stvaranje veće 'dodate' vrednosti za proizvode. Organizacija lanca vrednosti čini sintezu aktivnosti koje se obavljaju u cilju proizvodnje, pakovanja, dizajniranja, marketiranja, isporuke i podrške njenim proizvodima. U proizvodnji sušene šljive sa košticom, pri prosečnoj proizvodnji od 112 kg /dan i prosečnoj prodajnoj ceni od 350 din/kg, ostvarena dobit je iznosila 18.237 din/dan (za 24 sata sušenja). Pri prosečnom randmanu 1:4, odnosno ukoliko se od 100 kg sveže šljive može proizvesti 25 kg sušene šljive vlažnosti 26%, onda je dodata vrednost sušene šljive veća za oko 6 puta u odnosu na svežu šljivu. Prema ekonomskim pokazateljima utvrđenim u kalkulacijama u organskoj proizvodnji šljive postiže se pozitivan finansijski rezultat (dobitak) u iznosu od 3.940 €/ha. Cena koštanja šljive je 0,16 €/kg, a prodajna cena 0,38 €/kg. S obzirom da se u organskoj proizvodnji šljive postiže dobit, kao i da je cena koštanja po jedinici mere znatno niža u odnosu na prodajnu (otkupnu) cenu šljive (0,16 €/kg lt 0,38 €/kg) organska proizvodnja je ekonomski opravdana za proizvođača