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What would be the best method to compare to products on a question rated 1-7?

The current technique being utilized in my team is compare mean for the 2 groups using F test.

but doesn't it violates the very assumption of normal distribution of variable being compared?

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  • $\begingroup$ Short answer: Yes, in theory, but in practice no, as the $F$ test is extremely robust to violations against the normality assumptions. As long as you don’t have extremely small sample sizes, the means you’re comparing are approximately normally distributed (by the central limit theorem). $\endgroup$
    – Karl Ove Hufthammer
    Apr 1, 2015 at 8:25

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If your goal is comparing by the median of pairwise differences, you may apply non-parametric tests as the Mann-Whitney-U-Test (unpaired samples) or the Wilcoxon Test (paired samples).

If your sample is large, please check this discussion for options:

When to use the Wilcoxon rank-sum test instead of the unpaired t-test?

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