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# Can you use ANOVA with unequal sample sizes?

## Can you use ANOVA with unequal sample sizes?

The short answer: Yes, you can perform a one-way ANOVA when the sample sizes are not equal. Equal sample sizes is not one of the assumptions made in an ANOVA.

Can you do 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.

### Why can unequal sample sizes be a problem for ANOVA?

Problems with Unequal Sample Sizes Unequal sample sizes can lead to: Unequal variances between samples, which affects the assumption of equal variances in tests like ANOVA. Having both unequal sample sizes and variances dramatically affects statistical power and Type I error rates (Rusticus & Lovato, 2014).

Can you do ANOVA with unequal variances?

If your groups have unequal variances, your results can be incorrect if you use the classic test. On the other hand, Welch’s ANOVA isn’t sensitive to unequal variances.

## Can I do a t-test with unequal sample sizes?

Even though you can perform a t-test when the sample size is unequal between two groups, it is more efficient to have an equal sample size in two groups to increase the power of the t-test.

How do you compare two datasets with different sample sizes?

One way to compare the two different size data sets is to divide the large set into an N number of equal size sets. The comparison can be based on absolute sum of of difference. THis will measure how many sets from the Nset are in close match with the single 4 sample set.

### How do you compare two samples with different sizes?

How do you compare datasets with different sample sizes?

Popular Answers (1) One way to compare the two different size data sets is to divide the large set into an N number of equal size sets. The comparison can be based on absolute sum of of difference. THis will measure how many sets from the Nset are in close match with the single 4 sample set.

## How do you know if ANOVA variance is equal or unequal?

There are two ways to do so:

1. Use the Variance Rule of Thumb. As a rule of thumb, if the ratio of the larger variance to the smaller variance is less than 4 then we can assume the variances are approximately equal and use the Student’s t-test.
2. Perform an F-test.

How do you compare data with different sample sizes?

### How does unequal sample size affect power?

If unequal sample sizes are paired with unequal variances, this can result in dramatic differences in power and inflated or reduced type I error rates. values for the standard deviations. If standard deviations were smaller, power would be greater and if standard deviations were greater, power would be reduced.

Can you do at test with unequal sample sizes?

Even though you can perform a t-test when the sample size is unequal between two groups, it is more efficient to have an equal sample size in two groups to increase the power of the t-test. Welch’s t-test is for unequal variance data.

## Are unequal sample sizes a problem in ANOVA?

When Unequal Sample Sizes Are and Are NOT a Problem in ANOVA. 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.

What is the statistical power of an unequal sample size?

Power with Unequal samples The statistical power of a hypothesis test that compares groups is highest when groups have equal sample sizes. Power is based on the smallest sample size, so while it doesn’t hurt power to have more observations in the larger group, it doesn’t help either.

### When to use a weighted least squares ANOVA?

Otherwise, you might want to try a Weighted Least Squares ANOVA, using the inverse of the variance of each group as the weight. It’s a good option when variances are unequal but normality is met. You haven’t given me enough information to answer.

How unbalanced are the group sizes in SPSS?

The group sizes are very unbalanced (Group 1=98, Group 2=366, Group 3=180, Group 4=22, Group 5=10). I want to know if the mean outcome scores are significantly different between the groups, AND which ones are different, using SPSS.