Group size and measures of group-level properties: An examination of eta-squared and ICC values
研究了单因素随机效应ANOVA中的eta平方值在估计群体层面属性时，因群体规模导致的偏差，并通过模拟验证了偏差条件，最后提出了修正方法和不等群体规模下的估计指南。
The eta-squared (η2) from a one-way random effects ANOVA is an index commonly used to estimate group-level properties of data in multilevel research. Under some circumstances, however, η2 values provide biased estimates of the group-level properties. Biased estimates occur because the magnitude of the 1.12 in a one-way rando m effects ANOVA is partially a function of group size. In this paper, the relationship between group size and η is described, and a simulation verifying the relationship between group size and 112 is conducted. The simulation demonstrates the conditions under which η does and does not provide a biased estimate of group-level properties. The paper concludes by (a) discussing corrections for η2, and (b) providing guidelines for calculating estimates of group-level properties in samples having unequal group sizes.