Hi there, I'm hoping someone may be able to clarify:
I have two independent groups one patient group and one control group and I am wanting to compare their scores on the Beck Depression Inventory (BDI)
When doing normality testing to check whether to use a parametric t test or non parametric mann whitney U, should I be checking the normality of each groups scores separately or the whole sample (including patients and controls)?
1. As in do you check normality for the the patient groups BDI scores and then seperately the control group BDI scores?
2. If this is the case and one group comes back as their BDI scores being normally distributed and the other as abnormal do you do non parametric testing as one of the groups isnt normally distributed on that variable?
Thank you in advance for your help on this,
BW
Iona
I have two independent groups one patient group and one control group and I am wanting to compare their scores on the Beck Depression Inventory (BDI)
When doing normality testing to check whether to use a parametric t test or non parametric mann whitney U, should I be checking the normality of each groups scores separately or the whole sample (including patients and controls)?
1. As in do you check normality for the the patient groups BDI scores and then seperately the control group BDI scores?
2. If this is the case and one group comes back as their BDI scores being normally distributed and the other as abnormal do you do non parametric testing as one of the groups isnt normally distributed on that variable?
Thank you in advance for your help on this,
BW
Iona