HATİCE TÜL KÜBRA AKDUR, DENİZ ÖZONUR, HÜLYA BAYRAK

A Comparisonof Confidence Interval Methods of Fixed Effectin Nested Error Regression Model

Doğrusal karışık etki modelleri, zooloji, biyoloji ve eğitim gibi bilimin birçokalanında popüler ve güçlü bir araçtır. Bu modellerde sabit etki parametrelerinintahminleri hata ve rasgele etki terimlerinin varyanslarına bağlıdır. Rasgeleetkilerin dağılımları bilinmediğinde veya yeterli sayıda örnek bulunamadığında standart metodlar doğru sonuç vermeyebilir. Karışık etki modellerinin özel bir haliolan iç içe hata regresyon modelinin sabit etki parametresi için varolan güvenaralığı metodları arasında parametrenin gerçek değerini kapsama olasılığı bakımından en iyi olan güven aralığı metodu aranmıştır. Standart ve parametrikbootstrap-tabanlı güven aralığı metodları iç içe hata regresyon modeli içinsimülasyon çalışmasında küçük örnek çaplarında karşılaştırılmıştır. Zayıfkorelasyonda parametrik-bootstrap metodları daha iyi sonuçlar vemiştir. Profilolabilirlik metodu orta ve güçlü korelasyonlarda daha iyi sonuçlar sağlamıştır.

İç İçe Hata Regresyon Modelinde Sabit Etki Parametresi için Güven Aralığı Metodlarının Karşılaştırılması

Linear mixed-effects models are very popular and powerful tools inmany scientific fields such as zoology, biology, and education. Estimators of fixedeffects do not only depend on the variances of error terms but they also depend onrandom terms in mixed-effect models. When the distributions of random effects are unknown or enough sample size cannot be obtained, standard methods may fail. This study aims to determine a promising confidence interval method amongexisting methods in terms of coverage probability of true value of parameter.Standard and parametric bootstrap-based confidence interval methods for nestederror regression model were compared in the simulation study under smallsamples. It is observed that parametric bootstrap-based method provides bettercoverage rates for small intra-correlation and profile likelihood method usuallyprovides better results for moderate and strong correlation.

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