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
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-------------------------------------------
Richard Williams, Notre Dame Dept of Sociology
OFFICE: (574)631-6668, (574)631-6463
HOME: (574)289-5227
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