Analyzing one-way experiments: a piece of cake of a pain in the neck?

Statistics may be intricate. In practical data analysis many researchers stick to the most common methods, not even trying to find out whether these methods are appropriate for their data and whether other methods might be more useful. In this paper I attempt to show that when analyzing even simple one-way factorial experiments, a lot of issues need to be considered. A classical method to analyze such data is the analysis of variance, quite likely the most often used statistical method in agricultural, biological, ecological and environmental studies. I suspect this is why this method is quite often applied inappropriately: since the method is that common, it does not require too much consideration-this is how some may think. An incorrect analysis may provide false interpretation and conclusions, so one should pay careful attention to which approach to use in the analysis. I do not mean that one should apply difficult or complex statistics; I rather mean that one should apply a correct method that offers what one needs. So, various problems concerned with the analysis of variance and other approaches to analyze such data are discussed in the paper, including checking within-group normality and homocedasticity, analyzing experiments when any of these assumptions is violated, outliers presence, multiple comparison procedures, and other issues.Realizar análises estatísticas pode ser complicado. Em situações práticas muitos pesquisadores utilizam os procedimentos de análise mais comuns, sem investigar se os mesmos são apropriados para os seus resultados, ou mesmo se há outros métodos que poderiam ser mais adequados. Nesse artigo buscarei mostrar que mesmo na análise de experimentos de classificação simples (com um único fator) vários aspectos precisam ser considerados. A forma clássica de análise desse tipo de dados é a análise de variância, que é provavelmente o método estatístico mais usado na agricultura, biologia, ecologia e estudos de meio ambiente. Suspeito que essa é a razão pela qual tal método é frequentemente usado de forma inapropriada: uma vez que ele é muito usado, não suscita maiores considerações. Imagino que seja esse raciocínio que muitos pesquisadores devam empregar. Análises incorretas podem fornecer falsas interpretações e conclusões, e dessa forma é importante prestar atenção na escolha do procedimento a ser usado na análise. Não estou sugerindo que algum método difícil ou complexo deva ser usado, mas sim que um método correto seja adotado, de forma a fornecer os resultados adequados. Dessa forma, vários problemas relacionados à análise de variância e outras abordagens para analisar esse tipo de dados são discutidas nesse artigo, incluindo verificações de normalidade e homogeneidade de variâncias, análise de experimentos com violação dessas pressuposições, presença de dados discrepantes, testes de comparações múltiplas, além de alguns outros problemas

Princípios básicos na confecção de gráficos

Data visualization is a very important aspect of data analysis and of presentation. Focusing on the latter, this paper discusses various elements of constructing graphs for publications. Bad and good graphs are compared, and a checklist with graphical elements to be used while creating graphs is proposed.A visualização de dados é um aspecto importante da análise de dados e de sua apresentação. Nesse ponto de vista enfocam-se vários elementos da construção de gráficos para publicações. Gráficos ruins e bons são comparados, e uma lista de checagem de elementos de composição gráfica é proposta para ser utilizada durante a confecção de gráficos

How have the Eastern European countries of the former Warsaw Pact developed since 1990? A bibliometric study

Did the demise of the Soviet Union in 1991 influence the scientific performance of the researchers in Eastern European countries? Did this historical event affect international collaboration by researchers from the Eastern European countries with those of Western countries? Did it also change international collaboration among researchers from the Eastern European countries? Trying to answer these questions, this study aims to shed light on international collaboration by researchers from the Eastern European countries (Russia, Ukraine, Belarus, Moldova, Bulgaria, the Czech Republic, Hungary, Poland, Romania and Slovakia). The number of publications and normalized citation impact values are compared for these countries based on InCites (Thomson Reuters), from 1981 up to 2011. The international collaboration by researchers affiliated to institutions in Eastern European countries at the time points of 1990, 2000 and 2011 was studied with the help of Pajek and VOSviewer software, based on data from the Science Citation Index (Thomson Reuters). Our results show that the breakdown of the communist regime did not lead, on average, to a huge improvement in the publication performance of the Eastern European countries and that the increase in international co-authorship relations by the researchers affiliated to institutions in these countries was smaller than expected. Most of the Eastern European countries are still subject to changes and are still awaiting their boost in scientific development

Novel approach to automated flow titration for the determination of Fe(III)

A novel approach to automated flow titration with spectrophotometric detection for the determination of Fe(III) is presented. The approach is based on the possibility of strict and simultaneous control of the flow rates of sample and titrant streams over time. It consists of creating different but precisely defined concentration gradients of titrant and analyte in each successively formed monosegments, and is based on using the calculated titrant dilution factor. The procedure was verified by complexometric titration of Fe(III) in the form of a complex with sulfosalicylic acid, using EDTA as a titrant. Fe(III) and Fe(II) (after oxidation to Fe(III) with the use of H2O2) were determined with good precision (CV lower than 1.7%, n = 6) and accuracy ( | RE | lower than 3.3%). The approach was applied to determine Fe(III) and Fe(II) in artesian water samples. Results of determinations were consistent with values obtained using the ICP–OES reference method. Using the procedure, it was possible to perform titration in 6 min for a wide range of analyte concentrations, using 2.4 mL of both sample and titrant

Does Genetic Distance of Parental Forms Affect Specific Combining Ability and Heterosis Eff ects in F1 and F2 of Spring Rape Diallel Cross?

This paper aims to probe into relationships between genetic diversity of inbred lines, estimated through the Mahalanobis distance and the effects of specific combining ability (SCA) and heterosis. The SCA and heterosis effects were analyzed for nine quantitative traits of eight inbred lines and their diallel cross hybrids of spring rape. The field experiments (with F1 and F2 generations) were carried out in a partly balanced square design with four replications. The results show that the Mahalanobis distances for inbred lines and SCA effects of the hybrids were mostly positively correlated. However, the Mahalanobis distances were usually not related, or very weakly, with the heterosis effects. On this basis we conclude that it is possible that the genetic diversity of crossed lines does not have to affect heterosis effects in the hybrids derived from the crossing. Since, as far as could be determined, this is the first conclusion of this type in literature, it calls for further research to study this phenomenon

Nowoczesna technologia - szansa czy zagrożenie dla ochrony dziedzictwa narodowego

Trudno wyobrazić sobie funkcjonowanie współczesnego społeczeństwa bez zaawansowanych technologii. Masowy dostęp do telewizji czy Internetu otwiera przed nami wiele możliwości. Żyjemy w społeczeństwie informacyjnym, które cechuje łatwy dostęp do wiedzy i wiele udogodnień towarzyszących codziennym czynnościom. Ważne jest, aby umiejętnie wykorzystywać możliwości, jakie dają nam nowoczesne technologie. Ma to istotne znaczenie w odniesieniu do edukacji, polskiego dziedzictwa narodowego i szeroko pojętej kultury. Coraz częściej możemy zwiedzać jakieś miejsce czy uczestniczyć w życiu kulturalnym bez wychodzenia z domu. Niniejszy artykuł stanowi analizę wpływu nowoczesnych technologii na formy ochrony i upowszechniania dziedzictwa narodowego. Przedstawiono w nim teorię modernizacji, która opisuje etapy rozwoju społeczeństwa, by pokazać, że pomimo masowego rozwoju technologii nie każdy ma taką samą możliwość skorzystania z nich. Internet bez wątpienia jest bardzo pożytecznym narzędziem, jednak należy pamiętać o zachowaniu ostrożności w korzystaniu z jego zasobów

Impact of future land use change on large carnivores connectivity in the Polish Carpathians

The Polish Carpathians, like many mountain areas in Europe, are currently facing dynamic land use changes that will shape their future landscapes. As there are many different possible scenarios of potential change, we compared three different land use scenarios up until the year 2060 and assessed their impact on the potential habitat connectivity of two large carnivores—wolf (Canis lupus) and lynx (Lynx lynx). We first analysed the main directions of change within and outside the pan-European wildlife corridor located in the western part of the Polish Carpathians. Then we calculated and compared least-cost paths among randomly selected points for each land use scenario separately. Our results showed that the main direction of change—forest cover increase—may positively influence habitat connectivity for both wolf and lynx. However, due to the future spread of settlements, this positive impact might be locally limited. Therefore, to realise the potential conservation opportunities resulting from on-going land use changes, adequate orientation of spatial planning towards habitat connectivity is crucial