Greetings,

My objective is to conduct a 2-way anova (equal sample sizes/246 samples) in R. After running the Shapiro-Wilk normality test on the residuals, I am getting a p value of =.0011 which signifies that the distributions are not normally distributed. However, the histogram of errors and the Q-Q plot(attached) indicate that the nonnormality is at both extremes. A colleague looked at the plots and his recommendation was that I use us an ANOVA rather a non-parametric test as long as I included the Q-Q plot and/or histogram to support the decision. Therefore, I am wondering if it is acceptable to run a 2-way anova with this data. If it is not acceptable, what non-parametric test can I use (using R) in place of the 2-way anova?

Thanks, very much,

Ben

My objective is to conduct a 2-way anova (equal sample sizes/246 samples) in R. After running the Shapiro-Wilk normality test on the residuals, I am getting a p value of =.0011 which signifies that the distributions are not normally distributed. However, the histogram of errors and the Q-Q plot(attached) indicate that the nonnormality is at both extremes. A colleague looked at the plots and his recommendation was that I use us an ANOVA rather a non-parametric test as long as I included the Q-Q plot and/or histogram to support the decision. Therefore, I am wondering if it is acceptable to run a 2-way anova with this data. If it is not acceptable, what non-parametric test can I use (using R) in place of the 2-way anova?

Thanks, very much,

Ben

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