This question follows my previous one. I will now provide my data in order to help you help me :)
As previously said, I have N=42 from a controlled experiment. People made a questionnaire assessing their mood and then played a videogame. They obtained a score from the game.
According to the questionnaire score, they may either be considered as "negative", "neutral" or "positive", respectively represented by the colors red, grey and green.
The following is the plot of the untouched data.
I would like to do some hypothesis testing on score means, like Mean(positive people) > Mean(neutral people).
As I learned from the previous question, if the data is approximately Normal, I can use the T-test. Because histogram does not show interesting facts, I bootstrapped the score mean.
What follow are the results of the bootstrap
Call: boot(data = Tol$Tol.Score, statistic = mean.fun, R = 1500, sim = "ordinary") Bootstrap Statistics : original bias std. error t1* 2817.702 4.079778 91.06932
How much am I safe to perform the tests using the T-test? Shall I use a permutation test instead? Other thoughts?
Extra question: there is one subject that I consider as an outlier. He/she obtained a score < 5. What should I do with it? From what I learned, me shall never remove the outliers. But, since N is 42, it particularly affects the mean of its class (i.e., neutral)
Thank you again for your help.
Context: experiment that will be part of my MSc thesis and maybe a scientific paper.
Update: the dotted colored lines are the mean of scores the three groups