How to use G*power to calculate sample size for MANOVA?

Hi, I want to perform an a priori power analysis to determine the sample size for my study. I have one between subject variable with two levels (I assume number of groups = 2), three dependent variables (I assume response variables = 3). I am just interest in the main- and mediation effects. Alpha and Power are specified in the picture. Now, I was wondering about the effect-size categories (small, medium, large) because I cannot find anything about Pillai's V. What would be a medium effect size for f^2 (V)? Also, I thought that for MANOVAs, the partial eta-squared is indicating the effect size?

Best!

Can anyone please advised me on calculating sample size using Gpower? I want to see the effect of an intervention( independent variable: 2groups) on mental health (continuous) of participants and I have considered baseline outcome measure as a covariate? How can I calculate the sample size in this case? Furthermore, my two secondary outcomes (both are in continuous scale) are also affected by intervention according to the previous literature. In such case, do I have to consider them as a covariate? I am confused on numerator df and don't know what to put in both of these instances?

I need to use G*Power for my sample size per my university. When I look at my population it is 76 students. I have one independent variable (the two treatment groups, use of audiobooks vs. no use of audiobooks) and two dependent variables (reading comprehension and motivation to read). I am trying to figure out what all the settings are and where to put the population. I will be doing 2 groups one who get the intervention and one who does not. I will be doing a pre-test/post-test to determine if their comprehension levels went up and if their motivation to read went up during the intervention stage. I have attached the two ideas I think I have for how to do G*Power. One is between factors and the other is within factors. I'm not sure which is the right one.

The issue I also have is if it is between factors, then it says the sample size is 106. I'm not sure how that is possible if the entire population is 76, how can you sample 106 of 76? This is why I'm so confused. I would think I have to enter the total population somewhere in G*Power but I don't see where. At any rate, please check out the screenshots below and help if you can!

Thanks for reading!

I am studying the Socioeconomic Profile on their Level of Satisfaction

in Remittance Services. I have 12 IV: X1 - age, X2 - gender, X3- educational attainment, X4-occupation, X5-income, X-6 marital x7-status, x8-number of children, x9 duration of stay in Thailand as OFW, x10- remittances amount, x11- frequency of remittances and x-12 purpose of sending money and 1 DV: (Y) Level of SATISFACTION of Remitters. I need to get the sample size: what should I input in the: Number of groups, number of predictors, and response variables: I will be using using an alpha of 0.05, a power of 0.80, and a small effect size (f = 0.10)

I am trying to calculate a required sample size using G Power for MANOVA analysis: I have one predictor variable/IV and three outcome variables. I will be using one group of participants all will complete all measures (self-report questionnaires).

I am uncertain on a couple of things:

- Should I select MANOVA special effects and interactions or MANOVA global effects for my research design?

- For special effects and interactions it asks for number of groups but won't let me enter anything less than 2, what should I be entering here?

Thanks in advance

Please I want to know how to report MANOVA results from SPSS in APA format.

Thank you

Hi, all.

I am using G*power to perform a sensitivity analysis for a one-way MANOVA. The analysis suggested my study had a minimum detectable effect size of f^2(V) = .01.

I was not quite sure about this effect size f^2(V).

Is it just the effect size f^2 for pillai?

Gpower requires that df numerators be specified - can anyone advise how to estimate these in order to determine sample size? Thank you

I am struggling with a power analysis for a full within-subject study.

I have a 2 x 3 within subject design. I would like to calculate the sample size I need to find a significant interaction.

I go to G*Power, I select “repeated measures – within factors”.

Effect size f=.025

Alpha= .05

Power= .80

Number of groups: 1 (since the study is fully within subject, I guess this is the right value)

Number of measurements: Here is where I have some troubles. If I put 6 (3x2) I think the power analysis will tell me the chance I have to find a cell that is different from the other five.

Rather, I would like to compute a power analysis to test the 3x2 interaction.

Any idea how I can do that in g*power?