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**RE: 2x3 Mixed Design ANOVA**Oct 10, 2018 03:10 PM | Andrew Zalesky

RE: 2x3 Mixed Design ANOVA

Hi Ana,

your design matrix appears to be correct. I don't see any errors.

However, in the case of three time points, you may want to test a specific hypothesis such that connectivity strictly increases (or decreases) with time: time1 < time2 < time3. This will afford greater power than testing the general case in which all combinations are possible. While I am not familiar with your application, there may be some sequences (e.g. time2 > time3 > time1) that are not realistic to test and shoud therefore be excluded a priori.

Remember to include exchange blocks, given that your design appears to be repeated measures.

To test the main effect of time, the contrast for an F-test would be: [1 1 0 0 0.....]

Andrew

your design matrix appears to be correct. I don't see any errors.

However, in the case of three time points, you may want to test a specific hypothesis such that connectivity strictly increases (or decreases) with time: time1 < time2 < time3. This will afford greater power than testing the general case in which all combinations are possible. While I am not familiar with your application, there may be some sequences (e.g. time2 > time3 > time1) that are not realistic to test and shoud therefore be excluded a priori.

Remember to include exchange blocks, given that your design appears to be repeated measures.

To test the main effect of time, the contrast for an F-test would be: [1 1 0 0 0.....]

Andrew

*Originally posted by Ana Coelho:*Hi Dr. Zalesky,

I would like to do a 2x3 mixed ANOVA analysis and I was hoping that you could confirm that my design matrix is correct.

So, I have two groups (good and bad cognitive performers) and they were evaluated at 3 timepoints. I want to evaluate the interaction group x time

My data is organized as follows:

good1-time1

good1-time2

good1-time3

good2-time1

good2-time2

good2-time3

...

bad1-time1

bad1-time2

bad1-time3

bad2-time1

bad2-time2

bad2-time3

...

The design matrix for an example with 4 subjects will be something like this:

1 0 1 0 1 0 0 0

0 1 0 1 1 0 0 0

0 0 0 0 1 0 0 0

1 0 1 0 0 1 0 0

0 1 0 1 0 1 0 0

0 0 0 0 0 1 0 0

1 0 -1 0 0 0 1 0

0 1 0 -1 0 0 1 0

0 0 0 0 0 0 1 0

1 0 -1 0 0 0 0 1

0 1 0 -1 0 0 0 1

0 0 0 0 0 0 0 1

where the first 2 columns model time. columns 3 and 4 model interaction and last 4 columns the subject means.

Is this design correct?

Thanks in advance!

Best regards,

Ana

I would like to do a 2x3 mixed ANOVA analysis and I was hoping that you could confirm that my design matrix is correct.

So, I have two groups (good and bad cognitive performers) and they were evaluated at 3 timepoints. I want to evaluate the interaction group x time

My data is organized as follows:

good1-time1

good1-time2

good1-time3

good2-time1

good2-time2

good2-time3

...

bad1-time1

bad1-time2

bad1-time3

bad2-time1

bad2-time2

bad2-time3

...

The design matrix for an example with 4 subjects will be something like this:

1 0 1 0 1 0 0 0

0 1 0 1 1 0 0 0

0 0 0 0 1 0 0 0

1 0 1 0 0 1 0 0

0 1 0 1 0 1 0 0

0 0 0 0 0 1 0 0

1 0 -1 0 0 0 1 0

0 1 0 -1 0 0 1 0

0 0 0 0 0 0 1 0

1 0 -1 0 0 0 0 1

0 1 0 -1 0 0 0 1

0 0 0 0 0 0 0 1

where the first 2 columns model time. columns 3 and 4 model interaction and last 4 columns the subject means.

Is this design correct?

Thanks in advance!

Best regards,

Ana

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Title | Author | Date |
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Ana Coelho |
Oct 10, 2018 | |

Andrew Zalesky |
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Ana Coelho |
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Andrew Zalesky |
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