Can I use ANOVA for small sample size?
ANOVA is robust for deviations from normality when the sample sizes are small but equal. Investigators should try to design studies with equal numbers in each comparison group to promote the robustness of statistical tests.
Is ANOVA affected by sample size?
There is no equal sample size assumption for ANOVA. If your data satisfies the 3 assumptions (Normality, equality of variance and independence) you can run ANOVA. But if our sample size is very small (as in eg) the data may not satisfy assumptions and you will have to run Kruskall Wallis.
How does sample size affect F statistic?
If the sample sizes in an ANOVA increase, the variation about the means will diminish but the variation between means will not. So if the means are unequal, as sample sizes become larger, the F-statistic will tend to become larger and larger.
Which is the best program for mixed ANOVA?
Therefore, in most situations a multivariate approach, MANOVA, is recommended (Maxwell, Delaney, and Kelley 2004). To our knowledge, the only program that can accurately calculate power for mixed designs with greater than 2 levels is SAS’s PROC GLMPOWER (SAS 2015).
Can a two way ANOVA be used for a power analysis?
We can simulate a two-way ANOVA with a specific alpha, sample size and effect size, to achieve a specified statistical power. We will try to reproduce the power analysis in g*power (Faul et al. 2007) for an F-test from an ANOVA with a repeated measures, within-between interaction effect.
What should the power of a mixed factorial ANOVA be?
While g*power is a great tool it has limited options for mixed factorial ANOVAs. Let us setup a simple 2×2 design. For the 2-way interaction, the result should be a power of 91.25% with at total sample size of 46.
Can a repeated measures ANOVA be performed with SAS proc mixed?
SAS proc mixed is a very powerful procedure for a wide variety of statistical analyses, including repeated measures analysis of variance. We will illustrate how you can perform a repeated measures ANOVA using a standard type of analysis using proc glm and then show how you can perform the same analysis using proc mixed.