How to do paired t test with mean and sd?
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I would like to do paired t-test with mean and standard deviation and the number of sampling.
for A:mean =8.37 sd=0.53
B: mean=8.18 sd=0.16 number of samples for both A=B=44
Thanks.
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Accepted Answer
Star Strider
on 30 Aug 2016
To do it with only the means and standard deviations, you would have to write your own functions to calculate the one- and two-tailed t-probabilities, but fortunately with MATLAB that is not difficult:
Amean =8.37;
Asd=0.53;
Bmean=8.18;
Bsd=0.16;
N = 44;
v = 2*N-2;
tval = (Amean-Bmean) / sqrt((Asd^2+Bsd^2)/N); % Calculate T-Statistic
tdist2T = @(t,v) (1-betainc(v/(v+t^2),v/2,0.5)); % 2-tailed t-distribution
tdist1T = @(t,v) 1-(1-tdist2T(t,v))/2; % 1-tailed t-distribution
tprob = 1-[tdist2T(tval,v) tdist1T(tval,v)]
tprob =
0.0253 0.01265
So your groups are significantly different at alpha = 0.05.
The functions are correct, but you may want to check my ‘v’ and ‘tval’ calculations to be certain it they are correct to your experimental design. If they are not, change them appropriately.
5 Comments
Jeff Miller
on 10 Aug 2020
This old answer is not correct for a paired t-test. In that case the tval computation depends on the standard deviation of the difference scores A-B. You can compute the required value from Asd and Bsd if you also have the correlation of A with B.
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