- Atatürk Üniversitesi Ziraat Fakültesi Dergisi
- Vol: 5 Issue: 4
- ÇOKLU KARŞILAŞTIRMALARDA DAĞILIŞLA VE VARYANS YAPISIYLA İLGİLİ FARAZİYELERDEN AYRILIŞLARIN TEST ÖZEL...
ÇOKLU KARŞILAŞTIRMALARDA DAĞILIŞLA VE VARYANS YAPISIYLA İLGİLİ FARAZİYELERDEN AYRILIŞLARIN TEST ÖZELLİKLERİNE ETKİLERİ ÜZERİNDE BİR ARAŞTIRMA
Authors : Mehmet Cudi Okur
Pages : 0-0
View : 7 | Download : 2
Publication Date : 2010-12-15
Article Type : Research
Abstract :OZET Çoklu karşılaştırma testlerinde,n en fazla kullanılan LSD, Duncan, SNK ve Tukey testlerinin teorik özelliklerJ mc'elenerek temel fıa.raziyelerdeki aksamaların bu testleri nasıl etkileyeceği incelenmiştir. Simulasyon teknikleriyle teşkil tadilen .de· nemeler yeter sayıda1ekrarlanarak teıst!erin h:a.ta seviyeleri değişik'populasyonlar ve örnek genişlikleri ,esas alınarak tesbit edilmiştir. Normal şartlar için beklenen hata seviyeleri normal dağıliş ve homojen varyans faraziyelerininbozulduğu çeşitli durumlarda ortaya çıkan hata seviyeleriyle karşılaştırılarak hangi testlerin ne ölçüde etkilendiği incelenmiştir. Böylece, testlerin sağlamlık yönünden genel ve birbirlerine katşı durumları ortaya konmuştur. SUMMARY A Researoh on the Effects of Nonnormality and Variance Heterogeneity on the, Structure of Multiple Comparison Tests. When tıhe fixed model is u-sed, the aim of the analysis of variance is to determine the differences between the pQpulation means. As the F, test used for general nulI hypotıheses is not sufficient, the analysis of variance has got . to be completed by the multiple comparison tests. in order to detect tıhe differences among the population means, 'some parametric and non parametric test procedures have been developed. In this researah some properties of the parametric tests, s'llchas L.s. d., Duncan, SNK and Tukey, were investigated by using sampiing experiments. Multiple comparison tests are the main coİnponents of the analysis of variance. For this rea~ son, the validity of the comparisons depends on the accuracy of the knowledge thaıt is essential for the analysis of variance. There fore the assuımptioll's,of the aınalysiş of vaPİance can also 1?e .extended for the multiple compariıson tests. The oecurance of some departures from the underlying assu,mptions invıalidates the multiple compadsçm tests as the F tests, and causes wrong decisions. The error rate and theoreti· cal s;tıruoture of multiple comparisıon procedures are 'different /from eamother. Therefore : :tJlıe levels of type i and type 11 errOrs and their powers are not the SMTle. Because of the differences in tıhe error rates, the decisions and the results obtained by the use of these tests are different. In tlüs researc,h the sampling .experiments obtained by using Monte-Car1o methods. The error rates of the multiple comparison 'te9ts were investigated nder different conditiQns. The error rates obtained for the nonnal case have been taken as a crlterion to compare the other cases where some departures from the underlyıing assumptions. Taking two poission distribution witth the' parametres L = 2 'and L = 3, the departures from 'the nonnal1ty were considered. '57 Taking the samples of 5 groups, each with sample sizes of 3 and 7, type i error rates were estimated according to various error rate cri:teria. With the departures from the nQrmality the error rates of the Duncan, SNK, and Tukey's niethods were mareased. Th1s prıaotically arises when the sample sizes are smaIl. Effeots of the heterogeneity of the variances were also mvestigated for various combinamons of the group variançes. On each sampling, 4 and 5 groups ea'.ch having 3 and 7 observations were ohosen, Applying the analysis of v:ariance and the multiple 'comparison tests, type i error rates were calculated it has been revealed that high heterogeneity of variance ended up with the increase of type T error mates of multiple comparison tests except L.S.D.. In the case of low heterogeneity, however, did not prove accordingly giying slightly decreasing error rates.Keywords :