Last, we shouldn't really interpret our main effects because the interaction effect is statistically significant: F(2,114) = 4.9, p = 0.009. As explained in SPSS Two Way ANOVA - Basics Tutorial, we'd better inspect simple effects instead of main effects.Conclusion...
The eta-squared (η~2) 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, η~2 values provide biased esti- mates of the group-level properties. Biased estimates occur because the...
doi:10.1080/00220973.2014.907227ShiehGwowenRoutledgeJournal of Experimental EducationShieh, G. (2015). Sample size calculations for precise interval estimation of the eta- squared effect size. The Journal of Experimental Education, 83(2), 203-217....
Biased estimates occur because the magnitude of the η2 in a one-way random effects ANOVA is partially a function of group size. In this paper, the relationship between group size and η2 is described, and a simulation verifying the relationship between group size and η2 is conducted. The...
John T. E. Richardson.Eta squared and partial eta squared as measures of effect size in educational research,2011Richardson, J. T. E. (2011). Eta squared and partial eta squared as measures of effect size in educational research. Educational Research Review, 6(2), 135-147. doi:10.1016/j...