Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: st: ttest error message
From
Nick Cox <[email protected]>
To
[email protected]
Subject
Re: st: ttest error message
Date
Fri, 15 Mar 2013 19:56:22 +0000
You need the data selected to contain precisely 2 groups of the
variable named in -by()-.
"Precisely 2" means no less than 2, no more than 2.
That is because the -ttest- is designed to compare the means of your
variable, here -Return-, for 2 groups.
It can only find 1 such group.
You can check this by
tab `group_x' if inlist(group_`x',1,10) & Period==`z' & Sector==`j'
and for the combination that produces this error message, only one
distinct value of -`group_x'- will be shown.
Why I don't know: presumably a bug in your code.
Nick
On Fri, Mar 15, 2013 at 7:47 PM, Xixi Lin <[email protected]> wrote:
> Hi,
>
> I am using the following ttest code; however it shows the error
> message:1 group found, 2 required-----what does it mean?
>
> Here is my code:
> foreach x in x1 x2 x3 x4 x5 {
> foreach z of numlist 2/120 {
> foreach j of numlist 10 15 20 25 30 35 40 45 50 55 {
> qui ttest Return if inlist(group_`x',1,10) & Period==`z' &
> Sector==`j', by(group_`x') unequal
> display "`x'" "Period " "`z'" "Sector " "`j'" `r(p_l)'
> `r(p)' `r(p_u)'
> }
> }
> }
>
> Any help is appreciated!
>
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/faqs/resources/statalist-faq/
* http://www.ats.ucla.edu/stat/stata/