Stata-ttest的输出结果 [英] Stata -- output results of ttest
问题描述
我有group_id
的数据(1、2、3,依此类推).我必须通过group_id
运行t检验.下面,我提供了我想用于每个group_id
的代码.如何修改它,以便可以遍历group_ids
并获得所有t检验相结合的输出?将不胜感激.谢谢.
I have data by group_id
(1,2,3 and so on). I have to run a t test by group_id
. Below I am providing the code I think I will be using for each group_id
. How can I modify it so that I can loop over group_ids
and get an output with all the t tests combined? Will appreciate any help. Thanks.
ttest return, by(test_indicator) unequal
推荐答案
by
前缀可以为每个group_id
重复t检验,但是很难与其他代码结合使用.这是一个使用levelsof
和foreach
遍历每个id,运行ttests和post
结果到临时数据集的快速示例.然后将新的数据集加载并导出到.xls文件.
The by
prefix can repeat the t-test for each group_id
, but it is hard to combine with other codes. Here's a quick example of using levelsof
and foreach
to loop through each id, run ttests, and post
the results to a temporary dataset. The new dataset is then loaded and exported into an .xls file.
sysuse auto,clear
recode rep78 (1/3=1)(4/5=2),gen(id) // artificial group id
drop if missing(id) // ensure all casea have ids
tempname ttestparm
tempfile outfile
postfile `ttestparm' obs n1 n2 mu1 mu2 sd1 sd2 diff_b diff_se diff_p using `outfile',replace
levelsof id,local(idvals)
foreach i of local idvals {
ttest mpg if id==`i', by(foreign)
post `ttestparm' (`i') (`r(N_1)') (`r(N_2)') (`r(mu_1)') (`r(mu_2)') (`r(sd_1)') (`r(sd_2)') (`r(mu_1)'-`r(mu_2)') (`r(se)') (`r(p)')
}
postclose `ttestparm'
preserve
use `outfile',clear
export excel using "ttestout.xls", firstrow(variables) replace
restore
请注意,preserve
/restore
组合仅在需要处理更多原始数据的情况下才有用.
Note that the preserve
/restore
combo is only useful if there is more work to do with the original data.
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