A Cross-National Comparison of Intra-Class Correlation Coefficient in Educational Achievement Outcomes

Abstract

The plausible range of intra-class correlation coefficient (ICC) is essential for both a priori sample size calculations in planning cluster-randomized trials and statistical adjustments of misaligned analysis of clustered data in meta-analytic studies. Recent efforts to create databases for ICC in educational achievement outcomes are based on the studies published only in the US and Europe. The current study aims to extend the existing information for the plausible range of ICC values in educational achievement outcomes to a global scale by examining the distributional characteristics of two-level unconditional ICC estimates across countries participating in two international studies, TIMSS and PIRLS. The findings suggest large variability in the unconditional ICC estimates across countries, and current standards do not apply to every country. Researchers should look for country-specific ICC estimates in planning cluster-randomized trials and in comparing studies across countries

Keywords

• HLM,meta-analysis,intra-class correlation,multi-level modeling,TIMSS,PIRLS

A Cross-National Comparison of Intra-Class Correlation Coefficient in Educational Achievement Outcomes

Abstract

Kumeler-arasi (intra-class) korelasyon (KAK) katsayisinin olasi deger araliginin bilinmesi bireyler yerine kumelerin rastgele secilerek yapildigi arastirmalarda yeterli istatistiksel gucu elde etmek icin gerekli orneklem buyuklugunun arastirma oncesi hesaplamasinda kritik bir oneme sahiptir. Ayrica, meta-analitik calismalarda daha once yayinlanmis arastirmalarin verileri yorumlanirken, eger onceki arastirmalar hiyerarsik bir yapiya sahip veriyi dogrusal regresyona analizi ile analiz etmislerse, bu arastirmalarin sonuclarinin da istatistiksel olarak duzeltilmesi gerekmektedir. Bu duzeltme isleminde de, KAK katsayisinin tahmini deger araliginin bilinmesi gerekli olabilmektedir. Son zamanlarda, egitimde basariyi olcen test skorlari icin KAK katsayisinin tahmini deger araligini gosteren veri tabanlari olusturma cabalari sadece ABD ve baz i Avrupa ulkeleri ile sinirli kalmistir. Bu arastirma halihazirda egitimde basariyi olcen test skorlari icin KAK katsayisinin tahmini deger araligi hakkindaki bilgiyi kuresel olcekte genisletmeyi amaclamis, ve bu amacla iki uluslarasi calismanin, TIMSS ve PIRLS, verilerini kullanmistir. Arastirmani bulgulari KAK katsayisinin ulkeler arasinda onemli olcude degisebildigini gostermistir.

Keywords

• Hiyerarsik dogrusal modelleme, cok duzeyli modelleme, kumeler-arasi korelasyon, metaanaliz, TIMSS, PIRLS