in an RCT, I have 3 different treatment groups and one control group. The size of the control group is around 1000 while the size of other groups are just above 300.

To test balance I used ANOVA and Welch test, which show that several variables are unbalanced. Can I draw a smaller random sample (400) from the control group so that the sizes of all groups are relatively equal?

Actually after doing that only one variable is unbalanced. So would it cause any problems if I want to draw a smaller sample just for more balance? Thanks!


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