For my dissertation I am investigating help-seeking behaviour. Specifically, measuring help-seeking (actual and intended) using the GHSQ against different age groups, and also the effect of awareness of mental health campaigns (number of campaigns they are aware of). I am aware that gender may cause error variance, therefore have decided to measure gender also as a covariate. I am correct that to analyse this I would use a two-way ANCOVA? And how would I input this into GPower to calculate a sample size?
Thank you in advance!
Hi Amy,
I never needed to do this in GPower but I think you can use F tests as Test family and directly choose ANCOVA.
See attached a test I performed with some random data.
I hope this can help.
Regards.
Amy Henderson and Alcides Barrichello quite right but don't forget you can use the General Linear Model approach and treat ANCOVA as a regression. I believe if you had a repeated measure ANCOVA this would be much easier. See ANCOVA in this reference: https://b-ok.cc/book/3591248/4df2ac
Best, David Booth
Hello Amy Henderson. Is help-seeking behaviour (HSB) the outcome variable? If so, are actual and intended HSB both outcome variables? If so, are you using two univariate models or one multivariate model? Or are you using a repeated measures model, as David suggested? The 1989 article by Huberty & Morris is a good resource on these issues.
Article Multivariate Analysis Versus Multiple Univariate Analyses
I guess this is the questionnaire you are using, is it?
- https://documents.uow.edu.au/content/groups/public/@web/@gsm/documents/doc/uow090184.pdf
Also, you mentioned age groups. Do you have people's actual ages, or just the age groups they belong to? If you have actual ages, why are you treating age as categorical rather than continuous? Doing so discards information, and therefore reduces power. It also introduces an artificial step-function into the fitted values from your model.
Thanks for clarifying.
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