# Re: st: combining two variables

 From "Austin Nichols" To statalist@hsphsun2.harvard.edu Subject Re: st: combining two variables Date Wed, 7 Mar 2007 11:55:57 -0500

```Eleanor Friedman et al.--
I don't think any of the approaches below are robust
to unexpected twists in the data, something we
should all be careful of as a rule. Just to be
sure the data is as expected, I would:
clear
input  var1   var2
.      2
.      8
.      0
7      .
3      .
.      .
3      4
end
gen newvar1=max(var1,var2)
gen newvar2=min(var1,var2)
assert newvar1==newvar2
l var? newvar? if newvar1!=newvar2

Paswel Phiri Marenya <ppm3@cornell.edu> wrote:
```
```What to me is easier is something like:
gen var3 = var2
then replace var3=var1 in 4/5 and so on...although with a long data set it
may be tedious perhaps.
```
```Andrew H. Sidman <asidman@ic.sunysb.edu> wrote:
```
```While there is probably a faster way, I gen
temporary variables and recode the missing:
gen var1a = var1
gen var2a = var2
recode var1a var2a (. = 0)
gen newvar = var1a + var2a
drop var1a var2a
```
```Philipp Rehm <philipp.rehm@gmx.de> wrote:
```
```gen newvar=var1
replace newvar=var2 if newvar==.
```
```ricardo sierra <ricardo.sierra@gmail.com> wrote:
```
```egen newvar=rowtotal(var1 var2)
replace newvar=. if var1==. & var2==.
```

```nora@uchicago.edu wrote:
Now I have a question about combining the data from two
variables (in the same data set) into one variable. I want to
combine the variables in such a way that the data from one
variable can replace the missing values from the other. I have
created an example of what I am looking for below:
```
```*
*   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/
```