[R] T-test to check equality, unable to interpret the results.

[Steve Lianoglou]

Hi,

I was just going to send this when I saw Erik's post. He's right -- we  
can't say anything about your data, but we can say something about  
using a t-test.

I'm not a "real" statistician, so this answer isn't very rigorous, but  
might be helpful.

On Sep 16, 2009, at 2:55 PM, Robert Hall wrote:

> I believe the t-test checks for difference amongst the two sets, and  
> p-value
> < 0.05 means both thesets are statistically different.

A t-test is used to check if the difference in the mean of two samples  
is statistically significant.

The null hypothesis is that the two means are not different.

If you reject the null, it means you have reason to believe that the  
means of the two samples are different.

See the uses section here:

http://en.wikipedia.org/wiki/Student's_t-test

> Here while checking
> for dissimilarity the p-value is 0.3288, does it mean that higher the
> p-value (while t.test checks for dis-similarity) means more similar  
> the
> results are (which is the case above as the means of the results are  
> very
> close!)
> Please help me interpret the results..

Your intuition is essentially correct. In general, the higher the p- 
value (in any statistical test), the less confident you should be that  
rejecting the null hypothesis is a good idea.

-steve

--
Steve Lianoglou
Graduate Student: Computational Systems Biology
   |  Memorial Sloan-Kettering Cancer Center
   |  Weill Medical College of Cornell University
Contact Info: http://cbio.mskcc.org/~lianos/contact