help
help > RE: Longitudinal analysis with missed values
Oct 3, 2019 12:10 PM | Andrew Zalesky
RE: Longitudinal analysis with missed values
Hi Emma,
With 5 time points, testing the interaction between time and group will require a relatively large sample size.
As a starting point, I suggest to simplify your design. Perhaps consider testing an interaction with respect to the first and last time point only.
It should be possible to use exchange blocks with different sizes.
I am not sure what you mean by NaN connectomes. Do you mean missing values for certain connections in certain subjects?
Subjects with missing values at a given time point would not be represented as a row in your design matrix. You would not include a NaN in the row, you would just not include a row at all.
Andrew
Originally posted by Emma Muñoz-Moreno:
With 5 time points, testing the interaction between time and group will require a relatively large sample size.
As a starting point, I suggest to simplify your design. Perhaps consider testing an interaction with respect to the first and last time point only.
It should be possible to use exchange blocks with different sizes.
I am not sure what you mean by NaN connectomes. Do you mean missing values for certain connections in certain subjects?
Subjects with missing values at a given time point would not be represented as a row in your design matrix. You would not include a NaN in the row, you would just not include a row at all.
Andrew
Originally posted by Emma Muñoz-Moreno:
Dear Andrew,
Thanks for the toolbox, it is very useful!
I had a doubt to perform a longitudinal analysis. I want to evaluate the effect of time and the interaction between time and group in a longitudinal study. I have 2 groups and 5 timepoints, but not all the subjects were evaluated at the 5 timepoints. Therefore, in the exchange blocks vector to take into account measures of the same subject, I have included blocks with different number of elements: i.e. [1 1 1 1 1 2 2 2 2 3 3 3 3 3 ...].... but it does not work.
When I try to run NBS with this exchange blocks vector I get an error, because of the differences in block size.
I was wondering if adding NaN connectomes in the missed timepoints, but I don't know how NBS manage NaN and if it would make sense...
Is it possible to perform this kind of analysis with missed values? How?
Thanks in advance!!
Thanks for the toolbox, it is very useful!
I had a doubt to perform a longitudinal analysis. I want to evaluate the effect of time and the interaction between time and group in a longitudinal study. I have 2 groups and 5 timepoints, but not all the subjects were evaluated at the 5 timepoints. Therefore, in the exchange blocks vector to take into account measures of the same subject, I have included blocks with different number of elements: i.e. [1 1 1 1 1 2 2 2 2 3 3 3 3 3 ...].... but it does not work.
When I try to run NBS with this exchange blocks vector I get an error, because of the differences in block size.
I was wondering if adding NaN connectomes in the missed timepoints, but I don't know how NBS manage NaN and if it would make sense...
Is it possible to perform this kind of analysis with missed values? How?
Thanks in advance!!
Threaded View
| Title | Author | Date |
|---|---|---|
| Emma Muñoz-Moreno | Oct 3, 2019 | |
| Andrew Zalesky | Oct 3, 2019 | |
| Emma Muñoz-Moreno | Oct 3, 2019 | |
| Andrew Zalesky | Oct 5, 2019 | |
| Emma Muñoz-Moreno | Oct 7, 2019 | |