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help > RE: Design matrix and contrast for 2 way ANOVA, and f-value
Jan 23, 2020 12:01 AM | Andrew Zalesky
RE: Design matrix and contrast for 2 way ANOVA, and f-value
Yes this is basically correct, but I suggest plotting the
interaction so that you can fully understand the nature of the
effect.
Originally posted by davideit7:
Originally posted by davideit7:
Dear Dr. Zalesky,
sorry my question was not really clear.
My doubts are more related to the difference between contrasts:
[0 0 0 1] vs [0 0 0 -1]
Since I'm testing for the interaction between treatment (placebo/drug) and condition (A/B) using t-test, depending from the contrast I will address only one-sided alternative hypothesis, likewise for the main effect.
So I was wondering what are the differences between the two contrasts, for the interaction? I mean by looking at my design matrix:
I would say that the first contrast (0 0 0 1) will test whether connectivity is increased in the placebo_A and drug_B conditions, while the negative contrast (0 0 0 -1) will test for an increase in connectivity for placebo_B and drug_A condition. Is this correct?
Sincerly,
Davide
sorry my question was not really clear.
My doubts are more related to the difference between contrasts:
[0 0 0 1] vs [0 0 0 -1]
Since I'm testing for the interaction between treatment (placebo/drug) and condition (A/B) using t-test, depending from the contrast I will address only one-sided alternative hypothesis, likewise for the main effect.
So I was wondering what are the differences between the two contrasts, for the interaction? I mean by looking at my design matrix:
1-P_A 1 1 1 1
1-P_B 1 1 -1 -1
2-P_A 1 1 1 1
2-P_B 1 1 -1 -1
3-D_A 1 -1 1 -1
3-D_B 1 -1 -1 1
4-D_A 1 -1 1 -1
4-D_B 1 -1 -1 1
1-P_B 1 1 -1 -1
2-P_A 1 1 1 1
2-P_B 1 1 -1 -1
3-D_A 1 -1 1 -1
3-D_B 1 -1 -1 1
4-D_A 1 -1 1 -1
4-D_B 1 -1 -1 1
I would say that the first contrast (0 0 0 1) will test whether connectivity is increased in the placebo_A and drug_B conditions, while the negative contrast (0 0 0 -1) will test for an increase in connectivity for placebo_B and drug_A condition. Is this correct?
Sincerly,
Davide
Threaded View
| Title | Author | Date |
|---|---|---|
| Woomi Ban | May 30, 2019 | |
| davideit7 | Dec 5, 2019 | |
| Andrew Zalesky | Dec 6, 2019 | |
| davideit7 | Dec 6, 2019 | |
| Andrew Zalesky | Dec 7, 2019 | |
| davideit7 | Jan 20, 2020 | |
| Andrew Zalesky | Jan 21, 2020 | |
| davideit7 | Jan 22, 2020 | |
| Andrew Zalesky | Jan 23, 2020 | |
| Woomi Ban | Jun 10, 2019 | |
| Andrew Zalesky | Jun 10, 2019 | |
| Andrew Zalesky | Jun 1, 2019 | |