Contents
Does repeated measures ANOVA require equal sample sizes?
Because if you only have repeated measures, it is impossible to use different sample sizes. The very nature of the “repeated” in repeated measures means that there must be values for each subject in both groups. any subjects that only have a value in one group but not the other gets thrown out as invalid data.
Can you use two way ANOVA with unequal sample sizes?
According to Keppel (1993), there is no good rule of thumb for how unequal the sample sizes need to be for heterogeneity of variance to be a problem. So if you have equal variances in your groups and unequal sample sizes, no problem. If you have unequal variances and equal sample sizes, no problem.
What is a repeated-measures t-test?
The t-test assesses whether the mean scores from two experimental conditions are statistically different from one another. A repeated-measures t-test (also known by other names such as the ‘paired samples’ or ‘related’ t-test) is what you should use in situations when your design is within participants.
Can ANOVA have different sample sizes?
You can perform one way ANOVA with unequal sample sizes. You must consider the assumptions of Normality, equality of variance and independence ( that mentioned by Saigopal ) before using ANOVA and in a case of not correct assumption then you must use non-parametric test ( Kruskal-Wallis test ).
When are unequal sample sizes are and are not a problem?
In your statistics class, your professor made a big deal about unequal sample sizes in one-way Analysis of Variance (ANOVA) for two reasons. 1. Because she was making you calculate everything by hand. Sums of squares require a different formula* if sample sizes are unequal, but statistical software will automatically use the right formula.
How to calculate Sample Size for repeated measurements?
Unlike studies with independent observations, repeated measurements taken from the same participant are correlated, and the correlations must be accounted for in calculating the appropriate sample size. Some current software packages used for sample size calculations are based on oversimplified assumptions about correlation patterns.
Why are repeated measures used in population studies?
[…] Many researchers favor repeated measures designs because they allow the detection of within-person change over time and typically have higher statistical power than cross-sectional designs.
Why is it important to choose the right sample size?
Choosing the right sample size increases the chance of detecting an effect, and ensures that the study is both ethical and cost-effective. Repeated measures designs are widely used because they have advantages over cross-sectional designs.