[R] t test problem?

[Dimitris Rizopoulos]

Hi Liu,

before applying a t-test (or any test) you should first check if the 
assumptions of the test are supported by your data, i.e., in a t-test 
x and y must be normally distributed.

I hope it helps.

Best,
Dimitris

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/16/396887
Fax: +32/16/337015
Web: http://www.med.kuleuven.ac.be/biostat/
     http://www.student.kuleuven.ac.be/~m0390867/dimitris.htm


----- Original Message ----- 
From: "kan Liu" <kan_liu1 at yahoo.com>
To: <r-help at stat.math.ethz.ch>
Sent: Wednesday, September 22, 2004 9:52 AM
Subject: [R] t test problem?


> Hello,
>
> I got two sets of data
> x=(124738, 128233, 85901, 33806, ...)
> y=(25292, 21877, 45498, 63973, ....)
> When I did a t test, I got two tail p-value = 0.117, which is not 
> significantly different.
>
> If I changed x, y to log scale, and re-do the t test, I got two tail 
> p-value = 0.042, which is significantly different.
>
> Now I got confused which one is correct. Any help would be very 
> appreciated.
>
> Thanks,
> Liu
>
> __________________________________________________
>
>
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! 
> http://www.R-project.org/posting-guide.html
>