Participants (N=14) filled in two questionnaires at two points of time, and I want to see the correlation between the variables.
Is this sample size sufficient?
Also, should I have reverse coded the items before running the correlation analysis?
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Sign up to join this communityParticipants (N=14) filled in two questionnaires at two points of time, and I want to see the correlation between the variables.
Is this sample size sufficient?
Also, should I have reverse coded the items before running the correlation analysis?
Correlations are valid with fewer than 14 points, but they become more accurate with more data. Exactly how much more accurate depends on various things, but if the data are bivariate normal, the standard error is approximately
$SE(r) = \frac{(1-\rho^2)}{\sqrt{n-1}}$
However, with 14 points, the data clearly aren't going to be exactly bivariate normal. Still the denominator term should give you a rough idea: Accuracy goes up as the square root of N; with 4 times as many subjects, it's twice as accurate. And it's more accurate the higher the population correlation.
There is no reason to reverse code, that will just change the sign of the correlation.