Upper limb rehabilitation using robotic exoskeleton systems: a systematic review

Exoskeleton assisted therapy has been reported as a significant reduction in impairment and gain in functional abilities of stroke patients. In this paper, we conduct a systematic review on the upper limb rehabilitation using robotic exoskeleton systems. This review is based on typical mechanical structures and control strategies for exoskeletons in clinical rehabilitation conditions. A variety of upper limb exoskeletons are classified and reviewed according to their rehabilitation joints. Special attentions are paid to the performance control strategies and mechanism designs in clinical trials and to promote the adaptability to different patients and conditions. Finally, we analyze and highlight the current research gaps and the future directions in this field. We intend to offer informative resources and reliable guidance for relevant researcher’s further studies, and exert a far-reaching influence on the development of advanced upper limb exoskeleton robotic systems

The socio-political context of the application of fair selection models in the usa

In an earlier article, the psychometrics of various fair selection models that had been proposed in the United States of America in the late 1960s, early 1970s were presented. The purpose of the present article is to discuss the subsequent history of the application of these models in personnel selection in that country and to view its implications for the South African situation. Because the question of fair selection models ties in with the issue of affirmative action, a brief history of this issue as it pertains to personnel selection is also given. Key decisions of the American Supreme Court that have a bearing on this matter are also reviewed. The failure to widely apply these fair selection models may be attributed to the prevalent socio-political context which favours the preferential treatment of certain groups but is hesitant to specify the particulars and limits of such treatment. Opsomming 'n Vorige artikel het die psigometi-ika onderliggend aan verskeie billike keuringsmodelle wat in die laat sestigerjare, vroee sewentigerjare in die Verenigde State van Amerika voorgestel is, behandel. Die doel met die onderhawige artikel is om 'n oorsig te verskaf van die daaropvolgende geskiedenis van die toepassing van daardie modelle in personeelkeuring in daardie land, en om die implikasies daarvan vir die Suid-Afrikaanse situasie te belig. Omdat die aangeleentheid van billike keuringsmodelle verband hou met die kwessie van regstellende aksie, word 'n bondige geskiedenis van hierdie kwessie soos dit op personeelkeuring van toepassing is, ook verskaf. Sleutel-uitsprake van die Amerikaanse Hooggeregshof wat betrekking het op hierdie aangeleentheid word ook beskou. Die beperkte toepassing van hierdie billike keuringsmodelle kan toegeskryf word aan die heersende sosio-politieke konteks wat die voorkeurbehandeling van bepaalde groepe voorstaan, maar wat huiwerig is om die besonderhede en perke van sodanige behandeling te spesifiseer

Die effekvan punttoekenningstandaarde op die korrelasie tussen matriek- en universiteitsprestasie

The effect of marking standards on the correlation between matriculation and university performance. Marking standards differ between courses in the sense that the same group of students shows different course means in different courses. Goldman andWidawski (1976) proposed a within-persons procedure to adjust for such differences between university departments and Elliott and Strenta (1988) adjusted this procedure to perform such corrections between courses within departments. In this study the correlation between matriculation performance and university performance has been increased by applying this adjustment not only to university courses but also to matriculation subjects. Opsomming Punttoekenningstandaarde verskil tussen kursusse in die opsig dat dieselfde groep studente verskillende kursusgemiddeldes in verskillende kursusse toon. Goldman en Widawski (1976) het 'n tussenproefpersoonprosedure voorgestel om vir sodanige verskille tussen universiteitsdepartemente te korrigeer en Elliott en Strenta (1988) het dit aangepas om sodanige korreksies tussen kursusse binne departemente uit te voer. In hierdie ondersoek is die korrelasie tussen matriekprestasie en universiteitsprestasie verhoog deur hierdie aanpassing nie slegs op universiteit-kursusse nie, maar ook op matriekvakke toe te pas

The applicability of fair selection models in the South African context

This article reviews several models that are aimed at achieving fair selection in situations in which underrepresented groups tend to obtain lower scores on selection tests. Whereas predictive bias is a statistical concept that refers to systematic errors in the prediction of individuals' criterion scores, selection fairness pertains to the extent to which selection results meet certain socio-political demands. The regression and equal-risk models adjust for differences in the criterion-on-test regression lines of different groups. The constant ratio, conditional probability and equal probability models manipulate the test cutoff scores of different groups so that certain ratios formed between different selection outcomes (correct acceptances, correct rejections, incorrect acceptances, incorrect rejections) are the same for such groups. The decision-theoretic approach requires that utilities be attached to these different outcomes for different groups. These procedures are not only eminently suited to accommodate calls for affirmative action, but they also serve the cause of transparency. Opsomming Hierdie artikel verskaf 'n oorsig van verskeie modelle om billike keuring te verkry in situasies waar onderverteen-woordigende groepe geneig is om swakker op keuringstoetse te vaar. Terwyl voorspellingsydigheid 'n statistiese begrip is wat betrekking het op stelselmatige foute in die voorspelling van individue se kriteriumtellings, het keuringsbillikheid te make met die mate waarin keuringsresultate aan sekere sosiaal-politieke vereistes voldoen. Die regressieen gelyke-risiko-modelle maak aanpassings vir verskille in die kriterium-op-toetsregressielyne van verskillende groepe. Die konstante-verhoudings, voorwaardelike-waarskynlikheids- en gelyke-waarskynlikheidsmodelle manipuleer die toetsafkappunte van verskillende groepe sodat sekere verhoudings wat tussen keuringsresultate (korrekte aanvaardings, verkeerde aanvaardings, korrekte verwerpings, verkeerde verwerpings) gevorm word, vir verskillende groepe dieselfde is. Die besluitnemingsbenadering vereis dat nutwaardes geheg word aan die verskillende gebeurlikhede by verskillende groepe. Nie alleen is hierdie prosedures by uitnemendheid geskik om oproepe tot regstellende aksie te akkommodeer nie, maar hulle voldoen ook aan die eis van deursigtigheid

Coefficient alpha: Unnecessarily ambiguous; unduly ubiquitous

By means of simple numerical examples it is demonstrated how the value of coefficient alpha is determined by the size and sign of the item intercorrelations, the dimensionality of the items, and the number of items. Relatively high alphas may be obtained for multidimensional item data (as obtained under a violation of essential tau-equivalence). Dimensionality analyses should therefore precede internal-consistency analyses if unidimensional tests are required. Such analyses also may alert one to the possibility of negative alpha values. Alternative coefficients are mentioned for situations when essential tau-equivalence is in doubt

Statistical and extra-statistical considerations in differential item functioning analyses

This article briefly describes the main procedures for performing differential item functioning (DIF) analyses and points out some of the statistical and extra-statistical implications of these methods. Research findings on the sources of DIF, including those associated with translated tests, are reviewed. As DIF analyses are oblivious of correlations between a test and relevant criteria, the elimination of differentially functioning items does not necessarily improve predictive validity or reduce any predictive bias. The implications of the results of past DIF research for test development in the multilingual and multi-cultural South African society are considered. Opsomming Hierdie artikel beskryf kortliks die hoofprosedures vir die ontleding van differensiële itemfunksionering (DIF) en verwys na sommige van die statistiese en buite-statistiese implikasies van hierdie metodes. ’n Oorsig word verskaf van navorsingsbevindings oor die bronne van DIF, insluitend dié by vertaalde toetse. Omdat DIF-ontledings nie die korrelasies tussen ’n toets en relevante kriteria in ag neem nie, sal die verwydering van differensieel-funksionerende items nie noodwendig voorspellingsgeldigheid verbeter of voorspellingsydigheid verminder nie. Die implikasies van vorige DIF-navorsingsbevindings vir toetsontwikkeling in die veeltalige en multikulturele Suid-Afrikaanse gemeenskap word oorweeg

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