Add a column of differences to tables of summary statistics in Stata
If I make a two way summary statistics table in Stata using table
, can I add another column that is the difference of two other columns?
Say that I have three variables (a, b, c
). I generate quintiles on a
and b
then generate a two-way table of means of c
in each quintile-quintile intersection. I would like to generate a sixth column that is the difference of mean c
between the top and bottom quintiles of b
for each quintile of a
.
I can generate the table of mean c
for each quintile-quintile intersection, but 开发者_如何学编程I can't figure out the difference column.
* generate data
clear
set obs 2000
generate a = rnormal()
generate b = rnormal()
generate c = rnormal()
* generate quantiles for for a and b
xtile a_q = a, nquantiles(5)
xtile b_q = b, nquantiles(5)
* calculate the means of each quintile intersection
table a_q b_q, c(mean c)
* if I want the top and bottom b quantiles
table a_q b_q if b_q == 1 | b_q == 5, c(mean c)
Update: Here's an example of what I would like to do.
With the collapse
command you can create customized tables like the one you have in mind.
preserve
collapse (mean) c, by(a_q b_q)
keep if inlist(b_q, 1, 5)
reshape wide c, i(a_q) j(b_q)
gen c5_c1 = c5 - c1
set obs `=_N + 1'
replace c1 = c1[`=_N - 1'] - c1[1] if mi(a_q)
replace c5 = c5[`=_N - 1'] - c5[1] if mi(a_q)
replace c5_c1 = c5_c1[`=_N - 1'] - c5_c1[1] if mi(a_q)
list, sep(0) noobs
restore
Then you should obtain something like this in your output:
+-----------------------------------------+
| a_q c1 c5 c5_c1 |
|-----------------------------------------|
| 1 .2092651 .1837719 -.0254932 |
| 2 .0256483 -.0118134 -.0374617 |
| 3 .022957 .0586441 .0356871 |
| 4 .0431809 .0876745 .0444935 |
| 5 -.0859874 .0199202 .1059076 |
| . -.2952525 -.1638517 .1314008 |
+-----------------------------------------+
If you are not very familiar with Stata, the following help pages might be useful in understanding the code
help _variables
help subscripting
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