Alternative to One-way ANOVA unequal variance

I would like to compare the means across three groups of equal sizes (equal sample size is small, 21). The means of each group are normally distributed, but their variances are unequal (tested via Levene’s). Is a transformation the best route in this situation? Should I consider anything else first?

Answer

@JeremyMiles is right. First, there’s a rule of thumb that the ANOVA is robust to heterogeneity of variance so long as the largest variance is not more than 4 times the smallest variance. Furthermore, the general effect of heterogeneity of variance is to make the ANOVA less efficient. That is, you would have lower power. Since you have a significant effect anyway, there is less reason to be concerned here.

Update:

Attribution
Source : Link , Question Author : Diana E , Answer Author : Community

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