Statistical help (not independent samples)



Hello all,

I need a help in understanding what statistical test to use when I have 3 groups and the groups are not independent of each other (same person might be present in all the 3 groups). So, what test can I use to determine the differences between the means of groups.
I would have used ANOVA, but since the independence sampling assumption has been violated, what is an appropriate method?

Thanks in advance,