Since it is a repeated measure analysis, N is the number of cases you have multiple observations for. N = 50 would mean 50 cases with >=2 observations. Cheers, Björn.
Great video! This is the case when we measure the same thing under the same condition 3 times, right? But what do I select if I have a traditional 2x2 within ANOVA design with the factors indicating different conditions, let's say measuring RTs with 2 devices (computer, paper) and cognitive load (single-task, dual-task). Do I select just 1 group and 4 measurements in time?
Hi Stephan, thanks! That sounds like you only have one variable with two conditions and also two outcomes. In that case a MANOVA would be appropriate from my point of view. Best Regards, Björn.
@@statorials There are two independent within subject variables with two levels (Device: Computer/Paper and Task: Single-task, Dual task) so a 2w*2w design and the dependent variable is RT. So there are four conditions (Computer x Single-Task, Computer x Dual-Task, Paper x Single-Task and Paper x Dual-Task), which gives 4 measures. If we are interested in the main effects and potential interaction between the two indepdendent variables, what should be entered in G*Power to get a-priori sample size in this case?
Hi, Thank you for providing the tutorial. I have a couple of questions. I want to calculate the number of participants required for the following study. The study is longitudinal in nature and has two groups. Data is collected at two time points. The experiment has three conditions and a control condition. I am planning to compare the two groups across time and the different experimental conditions within each group and across time. How do I calculate the number of participants required in a group for a large effect size? Also, while selecting, should I select between factors, within or interaction? Thank you
Hi there, I would recommend doing a mixed ANOVA approach that covers between and within effects: th-cam.com/video/5AflJkhaln0/w-d-xo.html The estimated marginal means (posthoc-testing) you mentioned, cannot be directly considered in the sample size calculation though, which is not a deal breaker. Cheers, Björn.
You saved my life :)
Thanks for the positive feeback!
If you ever need your life saved again, you know the channel. ;-)
Cheers, Björn.
the Total Sample Size obtained is for each group or global?
Since it is a repeated measure analysis, N is the number of cases you have multiple observations for. N = 50 would mean 50 cases with >=2 observations.
Cheers, Björn.
Great video! This is the case when we measure the same thing under the same condition 3 times, right? But what do I select if I have a traditional 2x2 within ANOVA design with the factors indicating different conditions, let's say measuring RTs with 2 devices (computer, paper) and cognitive load (single-task, dual-task).
Do I select just 1 group and 4 measurements in time?
Hi Stephan, thanks! That sounds like you only have one variable with two conditions and also two outcomes. In that case a MANOVA would be appropriate from my point of view.
Best Regards, Björn.
@@statorials There are two independent within subject variables with two levels (Device: Computer/Paper and Task: Single-task, Dual task) so a 2w*2w design and the dependent variable is RT. So there are four conditions (Computer x Single-Task, Computer x Dual-Task, Paper x Single-Task and Paper x Dual-Task), which gives 4 measures. If we are interested in the main effects and potential interaction between the two indepdendent variables, what should be entered in G*Power to get a-priori sample size in this case?
Hi,
Thank you for providing the tutorial. I have a couple of questions. I want to calculate the number of participants required for the following study.
The study is longitudinal in nature and has two groups. Data is collected at two time points. The experiment has three conditions and a control condition. I am planning to compare the two groups across time and the different experimental conditions within each group and across time. How do I calculate the number of participants required in a group for a large effect size?
Also, while selecting, should I select between factors, within or interaction?
Thank you
Hi there, I would recommend doing a mixed ANOVA approach that covers between and within effects: th-cam.com/video/5AflJkhaln0/w-d-xo.html
The estimated marginal means (posthoc-testing) you mentioned, cannot be directly considered in the sample size calculation though, which is not a deal breaker.
Cheers, Björn.