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help > RE: repeated measures ANOVA + covariate
Apr 18, 2023 07:04 AM | Andrew Zalesky
RE: repeated measures ANOVA + covariate
Hi Maksym,
Yes - you are right.
The equivalent F-test is given by F=t^2.
There is a subtle difference between F and t in that t is always a one-sided test, whereas F is two-sided. So the results with t=3.1 will not necessarily be exactly the same as F=9.61, since F will consider positive and negative correlations whereas t will either consider positive or negative.
Finally, it is important to note that there is no right or wrong threshold. It is ok to match between t and F but it is also ok to consider other thresholds.
Andrew
Originally posted by Maksym Tokariev:
Yes - you are right.
The equivalent F-test is given by F=t^2.
There is a subtle difference between F and t in that t is always a one-sided test, whereas F is two-sided. So the results with t=3.1 will not necessarily be exactly the same as F=9.61, since F will consider positive and negative correlations whereas t will either consider positive or negative.
Finally, it is important to note that there is no right or wrong threshold. It is ok to match between t and F but it is also ok to consider other thresholds.
Andrew
Originally posted by Maksym Tokariev:
Dear Prof. Zalesky,
Thank you once again for the detailed explanations on designs and their implementation in NBS. I have another question and it is about statistical thresholding. At present, I'm doing a correlation analysis of subjects' connectivity with the age. From the forum pages I found that there are three ways of searching for correlations:
1. Positive correlations (t-test) | set up [0 1] contrast
2. Negative correaltion (t-test) | set up [0 -1] contrast
3. Both positive and negative correlations (F test) | set up [0 1] contrst and select F-test instead of t-test
In my analysis, the threshold for t-test is 3.1. The question is, does one have to adjust this threshold when selecting the F-test instead of t-test? As I understand, the relationship between the two values is F=t^2. As such, to compare the connectivity maps from both statistical measures I need to change the t=3.1 (ttest) to F=t^2=9.61 (F-test). By doing so, the adjusted threshold brings more similarities with the t-test, which makes it easier to compare. I attached the .pdf to illustrate my concern.
Thank you in advance for the answer.
Regards,
Maksym
Thank you once again for the detailed explanations on designs and their implementation in NBS. I have another question and it is about statistical thresholding. At present, I'm doing a correlation analysis of subjects' connectivity with the age. From the forum pages I found that there are three ways of searching for correlations:
1. Positive correlations (t-test) | set up [0 1] contrast
2. Negative correaltion (t-test) | set up [0 -1] contrast
3. Both positive and negative correlations (F test) | set up [0 1] contrst and select F-test instead of t-test
In my analysis, the threshold for t-test is 3.1. The question is, does one have to adjust this threshold when selecting the F-test instead of t-test? As I understand, the relationship between the two values is F=t^2. As such, to compare the connectivity maps from both statistical measures I need to change the t=3.1 (ttest) to F=t^2=9.61 (F-test). By doing so, the adjusted threshold brings more similarities with the t-test, which makes it easier to compare. I attached the .pdf to illustrate my concern.
Thank you in advance for the answer.
Regards,
Maksym
Threaded View
| Title | Author | Date |
|---|---|---|
| Maksym Tokariev | Mar 21, 2023 | |
| Andrew Zalesky | Mar 22, 2023 | |
| Maksym Tokariev | Mar 22, 2023 | |
| Andrew Zalesky | Mar 22, 2023 | |
| Maksym Tokariev | Apr 17, 2023 | |
| Andrew Zalesky | Apr 18, 2023 | |
| Andrew Zalesky | Mar 22, 2023 | |