Most statistics cannot be analyzed with 2 unequal in number groups, while some can. In analyzing one-way ANOVA for example, unequal sample sizes may be analyzed but can affect the homogeneity of variance assumption.
The two unequal in number groups regression analysis, paired-sample t-test... etc.. cannot be analyzed.
I disagree with Mahfuz. Paired-sample t-test, of course, requires equal Ns, but most regression methods, including ANOVA, do not. The homogeneity of variance assumption does not depend on equal cell sizes--rather, conventional wisdom has been that ANOVA results are more strongly affected by heterogeneity of variance with equal group sizes than with unequal. But homogeneity is assumed regardless.
But most methods can accommodate uneven sample sizes. This is often at a loss of power relative to balanced groups with the same total N, but there's nothing intrinsically harmful about unbalanced groups.
Ahmed, we might be able to help more if you can say more about your design and planned analyses.
Pat
- Badges
- Science method
- Similar topics
- Mathematics
- Statistics
- Statistical Modeling
- Analyses of Variance
- ANOVA