Comparing samples with different sizes

I have 6 groups of different observers that performed the same task but have different sizes:
A - 196
B - 195
C - 80
D - 35
E - 32
F - 48
Assuming that the variables are independent and data assume a non-para metric distribution, how can I compare these groups? Which is the best statistical test to do it?
Thank you very much!!


TS Contributor
There is no nonparamtric distribution. There are only nonparametric tests (tests which do not assume
a certain distribution of whatever). How exactely was task perfomance measured?

With kind regards

I sincerely apologize for the error. Thank you.

The observer's task was to select a color from a physical stimuli presented in a monitor. The selected color was automatically converted into two chromatic coordinates: a* and b*. And it is with these coordinates that we want to analyze. Did that helped?

Thank you!
Andreia Gomes


TS Contributor
I do not know what a chromatic co-ordinate is. Is it a continuous measurement (at least interval scaled)?
And do you want to compare a* and b* jointly between groups, or each co-ordinate separately?

With kind regards
a* or b* is a quantitative and continuous variable. Similar to the cartesian coordinates (x and y) in a two-dimensional space: it can take on negative or positive values. As they represent different colors, they should be evaluated separately. Do you need more information?