I am trying to determine differences in fish weights from 1st to 2nd sampling between a control group and 4 different treatment groups. My groups are unbalanced (control = 1 group, t1= 2 groups, with t2,t3,t4 = 3 groups). Originally I was told this shouldn't be a problem.
I've run a 2-way ANOVA and the Levene's test in SPSS is significant (0.017) but ANOVA is (0.018) and the significant factor is (.001). Is there a way to adjust for this or do I need to run a different stats test?
Otherwise I was thinking I may need to simplify and combine all the treatment groups and run a t-test, then run another t-test for the control to demonstrate there are differences between treated and non-treated fish. What do you think?
Ok so there are a total of 21 tanks of fish i.e. n= 21. We didnt have room for 22 tanks so one treatment group only had to 2 tanks. We attempted to run everything in triplicate so 3 of the treatment groups are triplicated. 1 treatment group is duplicated, and 1 group is the control (single). The weights of fish are tanks averages. The largest difference is a total of 22 grams, the smallest is a difference of less than 1 between tanks