Hi Richard,
Thank you very much for your prompt response! I did not use -ttest-
for several reasons:
First, I actually have a weight variale in my data and -ttest- does
not allow weights.
Second, I need compare means of many variables, so I want to quietly
run means calculation and comparison, then generate a table with -mat-
commands. In that table, I want to see p-value. So I have to calculate
it as Stata does not save it.
To me, the -lincom- seems to do what I want, but I want to confirm
this with people better in statistics and more familiar with Stata
than me. Please let me know if what I did is correct. Thanks a lot!
Best,
Lili
On Fri, Jun 20, 2008 at 4:24 PM, Richard Williams
<[email protected]> wrote:
> I'm probably missing something, but wouldn't it be a lot more
> straightforward just to use the ttest command, e.g.
>
> ttest mpg, by(foreign)
>
> At 04:57 PM 6/20/2008, Lili Yan wrote:
>>
>> Hi there,
>>
>> I need calculate the mean of two groups (say, native cars and foreign
>> cars) and do a t-test. However, I am not very sure if -lincom- is the
>> correct command after -mean-. Could anyone please let me know if the
>> following commands are right?
>>
>> mean mpg, over(foreign)
>> lincom [`var']0-[`var']1
>> di 2*ttail(r(df), abs(r(estimate)/r(se)))
>>
>> Thanks in advance!
>>
>> Best,
>> Lili
>> *
>> * For searches and help try:
>> * http://www.stata.com/support/faqs/res/findit.html
>> * http://www.stata.com/support/statalist/faq
>> * http://www.ats.ucla.edu/stat/stata/
>
> -------------------------------------------
> Richard Williams, Notre Dame Dept of Sociology
> OFFICE: (574)631-6668, (574)631-6463
> HOME: (574)289-5227
> EMAIL: [email protected]
> WWW: http://www.nd.edu/~rwilliam
>
> *
> * For searches and help try:
> * http://www.stata.com/support/faqs/res/findit.html
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
