Quote:>I have a stupid question. What is the difference between sign test and

>Signrank test? Please advice, Thanks. Based on my understanding,

>sign test is similar to one sample t-test

>sign rank test is similar to paired sample t-test

>Am I correct?

Either test could both be used in either situation (as could the

t-test: the paired t-test is simply a one-sample test applied to

difference scores). The principal difference is that the signed-rank

test uses information on the relative magnitude of differences,

whereas the sign test weights all differences the same if they are in

the same direction. In other words, the signed-rank test uses more

information about the data than the other, and is more powerful in

many cases. It is however somewhat vulnerable to failure when the

distribution of (difference) scores shows significant skew, in which

case the sign test may be preferred.

JW