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help > RE: 2-way ANOVA matrix design and contrast
May 23, 2017 08:05 AM | Andrew Zalesky
RE: 2-way ANOVA matrix design and contrast
Hi Jeff,
The design matrix and contrast you have given below are correct. The ones in your previous post are not correct. The two design matrices are not really equivalent in that way you are defining main effects and interaction.
Andrew
Originally posted by Jeff Jiang:
The design matrix and contrast you have given below are correct. The ones in your previous post are not correct. The two design matrices are not really equivalent in that way you are defining main effects and interaction.
Andrew
Originally posted by Jeff Jiang:
Hi Andrew,
Regarding to my last question, I also tried another design matrix and contrast:
intercept a b interaction
1 -1 -1 1
1 -1 -1 1
1 -1 1 -1
1 -1 1 -1
1 -1 1 -1
1 1 -1 -1
1 1 -1 -1
1 1 -1 -1
1 1 1 1
1 1 1 1
And contrast is [0 1 0 0] for main effect a, [0 0 1 0] for main effect b, and [0 0 0 1] for a*b interaction effect.
According to my understanding, this design and contrast should be equivalent to the ones in my last post (I also found that the FSL manual said these two are equivalent). However, I got totally different F-test results using NBS based on the two settings. Could you please help? Thanks.
Regards,
Jeff
Regarding to my last question, I also tried another design matrix and contrast:
intercept a b interaction
1 -1 -1 1
1 -1 -1 1
1 -1 1 -1
1 -1 1 -1
1 -1 1 -1
1 1 -1 -1
1 1 -1 -1
1 1 -1 -1
1 1 1 1
1 1 1 1
And contrast is [0 1 0 0] for main effect a, [0 0 1 0] for main effect b, and [0 0 0 1] for a*b interaction effect.
According to my understanding, this design and contrast should be equivalent to the ones in my last post (I also found that the FSL manual said these two are equivalent). However, I got totally different F-test results using NBS based on the two settings. Could you please help? Thanks.
Regards,
Jeff
Threaded View
Title | Author | Date |
---|---|---|
Jeff Jiang | May 22, 2017 | |
Jeff Jiang | May 23, 2017 | |
Andrew Zalesky | May 23, 2017 | |
Jeff Jiang | May 23, 2017 | |
Andrew Zalesky | May 23, 2017 | |
Jeff Jiang | May 24, 2017 | |
Andrew Zalesky | May 24, 2017 | |