# Thread: Paired t test or two sample ANOVA

1. ## Paired t test or two sample ANOVA

Hi,

The experiment is investigating whether IQ changes based on certain training (there are 2 courses and a control - nothing). I have the IQ of individuals before and after the courses and I want to know if the IQ will increase as a result of the courses, but not as a result of receiving no training.

The paired t test would require separating the data into groups based on the course, this would show if the IQs changed significantly within the groups but wouldn't show if the groups were significant from each other... Therefore I was thinking about the two sample anova. Is the two sample ANOVA the way to go?

I am also going to illustrate any changes in the IQs for each group, by calculating the differences from before and after. Would this calculation be something which I could statistically test? carrying out an ANOVA between the difference and the courses?

Thanks for taking the time to look at this for me!!

Hopefully its a lot simpler than I am making it!!

2. ## Re: Paired t test or two sample ANOVA

Usually best not to use difference scores: http://www.jstor.org/stable/2489447

Conventional approach here would be repeated measures ANOVA. The thing of primary interest would be the interaction between time and group (i.e., you expect the improvement to be greater in the treatment group).

Slightly more complicated with two treatment groups and one control, but you probably get the idea.

3. ## Re: Paired t test or two sample ANOVA

I forgot to mention that there were 50 different individuals for both the treatment groups and the control, does this make the repeated measures anova redundant?

If I am honest, this is a task set by my institution and I don't think it is suppose to be tricky in any way, I have tried using the difference scores and I can see that the data has been manipulated to agree with the hypothesis. If I were to use the difference scores, would I simply use an ANOVA with a tukey post hoc in order to see any significant difference between groups?