*Bounty: 50*

*Bounty: 50*

I have a test of a skill which will return a value between 0 and 30 for a participant as a measure of that skill. I have five ordinal groups of participants (they are corresponding to university level attainment – first years, honours students, PhD students, etc) and I intend to have a number of participants from each group take the test. I then intend on performing an ANOVA to investigate the difference in skill level across each group.

Although I have an idea of what I want to do, I want to be clear on a few of things:

- How can I determine that my results are statistically significant?
- How many participants should I take from each group (which are of varying sizes) to ensure that my results are reliable?
- How would I go about calculating the statistical power of the experiment?