help > RE: One sample or t-test
Sep 3, 2018  07:09 PM | Andrew Zalesky
RE: One sample or t-test
Hi Yin,

1) Yes correct.

2) If you would like to test for a negative effect, simply multiply your connectivity values by -1.You cannot test for both a negative and a positive effect using one-sample.

3) t-test is for testing other contrasts, such as between-group differences, correlations, etc. The one-sample test only tests the null hypothesis that connectivity values are 0. One-sample test is rarely used in practice.

Andrew

Originally posted by LJ Yin:
Hi Andrew,

I am trying to use NBS to analyze data. I have one group of subjects and I would like to test if the means of some connections are greater than or smaller than zero.
1) I chose one sample as the statistic analysis. And the design matrix is listed as follow:
1
1
1
1
...
I set the contrast of 1. Is this the correct way of performing the analysis?
2) According to the manual, "The one sample test randomly flips the sign of each data point for each permutation, which corresponds to a one-sided, one sample t-test. Note that the one sample test always assesses whether the mean is greater than zero, irrespective of the sign of the contrast vector." I guess the one sample test is only to test the positive effect, right? What if I would like to test both the positive and negative effect?
3) What's the difference between "one-sample" and "t-test"? Shouldn't I obtain the same result by using "one-sample" and "t-test"by applying the same design matrix and contrast like I mentioned above?

Best regards,
Lijun