There are 16 people in the dataset(using subjectID to identify them). Each year, when these people were ages 11, 12, 13, 14, and 15, they provided us a score $y$. We now want to know whether there is a significant difference between male and female people (in their average $y$ score). How could I do? I found that this dataset does not meet the normality assumption. And in "Male" group, say subject 45 will appear 5 times, subject 268 will appear 5 times as well... Could I just use the mean of this "Male" group to make comparison with the mean of "Female" group?
And I also wonder if I can use a fixed effect model to compare these two groups:
We can see the difference between "Male" group and "Female" group is 0.13521, and it is not significant at 5% level as its p-value=0.228 (cannot reject $H_0$:"genderM"=0). So could I just say the difference is not significant?