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help > Design matrix
Dec 14, 2017 06:12 PM | Alexia Bourgeois - University of Geneva
Design matrix
Hi Andrew,
I'm just beginning with NBS. I went through the forum and the manual but I'm still confused regarding the design matrix.
I have two groups of subject: one group of stroke patients scanned 3 times (Time Point 1, 2, 3) and 1 group of controls scanned only once (TP1).
I would like to compare the 3 time points across my group of patients, I guess this correspond to one-way ANOVA within subject analysis.
In this case, should I create the following matrice, here presented for two subjects: (P for patients, T for time point)
P1T1 1 0 1 0
P2T1 0 1 1 0
P1T2 1 0 0 1
P2T2 0 1 0 1
P1T3 1 0 0 0
P2T3 0 1 0 0
Echange block: [1 2 1 2 1 2]
Contrast F test [0 0 1 1] to compare here T1 vs T2?
Also Time point 1 and TP 3 are missing for two different patients. Should I remove these patients for this analysis?
Then to compare patients vs controls, I guess I have to select paired of time points to obtain a 2x2 model.
In this case I obtain this matrix (C for control, P for patients, T for Time point)
C1T1 0 1 1 0 0 0
C1T2 1 0 1 0 0 0
C2T1 0 1 0 1 0 0
C2T2 1 0 0 1 0 0
P1T1 0 0 0 0 1 0
P1T2 1 1 0 0 1 0
P2T1 0 0 0 0 0 1
P2T2 1 1 0 0 0 1
The 1st column correspond to the main effect of time -> F test - Contrast=[1 0 0 0 0 0] - Exchange blocks=[1 1 2 2 3 3 4 4]
The 2nd column correspond to the interaction between group x time -> t-test - Contrast=[0 -1 0 0 0 0] or [0 -1 0 0 0 0] - Exchange blocks=[1 1 2 2 3 3 4 4]
The fourth last columns correspond to the subject means. Should we automatically include it in the design matrix? What does it change?
Sorry for this long email but I'm quite lost! Thanks a lot in advance for your help and insights!
Regards,
Alexia
I'm just beginning with NBS. I went through the forum and the manual but I'm still confused regarding the design matrix.
I have two groups of subject: one group of stroke patients scanned 3 times (Time Point 1, 2, 3) and 1 group of controls scanned only once (TP1).
I would like to compare the 3 time points across my group of patients, I guess this correspond to one-way ANOVA within subject analysis.
In this case, should I create the following matrice, here presented for two subjects: (P for patients, T for time point)
P1T1 1 0 1 0
P2T1 0 1 1 0
P1T2 1 0 0 1
P2T2 0 1 0 1
P1T3 1 0 0 0
P2T3 0 1 0 0
Echange block: [1 2 1 2 1 2]
Contrast F test [0 0 1 1] to compare here T1 vs T2?
Also Time point 1 and TP 3 are missing for two different patients. Should I remove these patients for this analysis?
Then to compare patients vs controls, I guess I have to select paired of time points to obtain a 2x2 model.
In this case I obtain this matrix (C for control, P for patients, T for Time point)
C1T1 0 1 1 0 0 0
C1T2 1 0 1 0 0 0
C2T1 0 1 0 1 0 0
C2T2 1 0 0 1 0 0
P1T1 0 0 0 0 1 0
P1T2 1 1 0 0 1 0
P2T1 0 0 0 0 0 1
P2T2 1 1 0 0 0 1
The 1st column correspond to the main effect of time -> F test - Contrast=[1 0 0 0 0 0] - Exchange blocks=[1 1 2 2 3 3 4 4]
The 2nd column correspond to the interaction between group x time -> t-test - Contrast=[0 -1 0 0 0 0] or [0 -1 0 0 0 0] - Exchange blocks=[1 1 2 2 3 3 4 4]
The fourth last columns correspond to the subject means. Should we automatically include it in the design matrix? What does it change?
Sorry for this long email but I'm quite lost! Thanks a lot in advance for your help and insights!
Regards,
Alexia
Threaded View
Title | Author | Date |
---|---|---|
Alexia Bourgeois | Dec 14, 2017 | |
Leonardo Tozzi | Nov 19, 2019 | |
Leonardo Tozzi | Nov 18, 2019 | |
Andrew Zalesky | Nov 18, 2019 | |
Andrew Zalesky | Dec 16, 2017 | |
Alexia Bourgeois | Dec 19, 2017 | |
Andrew Zalesky | Dec 20, 2017 | |