How can I create a variable that stores the sample means of multiple variables?

[Zach Goldberg]

Greetings,

I'm running Stata 15.1 on OSX. I'd like to create a variable that stores the (separate) means of 4 different ordinal variables. If still unclear: once the variable is created and tabulated, I expect to see something like:
4.57
3.29
2.22
5.43

In attempting to create this variable, I tried the following:

egen sample_means=mean(intlwhts intlblks intlasns intlhsps)

Stata returns the following error message:

intlwhtsintlblksintlasnsintlhsps not found

The rowmean function would simply create an average of the 4 variables, which is not what I want. Any help here would be much appreciated. Thanks!

Example data:

* Example generated by -dataex-. To install: ssc    install    dataex
clear
input float(intlwhts intlblks intlasns intlhsps)
4 4 4 4
6 2 7 3
6 5 6 5
4 4 4 4
5 4 4 3
5 4 7 5
2 3 1 4
6 6 6 6
4 3 4 3
4 4 4 4
5 3 3 2
6 6 6 6
4 4 4 4
4 4 4 4
5 4 6 4
4 4 2 6
4 4 4 4
4 4 4 4
5 5 5 5
7 7 7 7
7 3 4 4
5 4 5 4
7 3 7 3
3 2 3 3
4 4 4 4
5 4 6 4
4 4 5 4
4 5 4 4
4 4 4 4
5 5 4 5
4 4 4 4
5 6 7 5
5 3 5 2
6 5 7 6
7 7 7 7
6 4 5 4
3 3 2 2
6 5 7 5
6 5 6 6
6 6 6 6
5 5 5 5
5 3 3 4
7 3 6 6
6 4 6 5
4 4 4 4
5 4 6 4
4 4 4 4
4 4 4 4
4 4 5 4
6 6 6 6
4 4 6 4
5 3 6 4
4 4 7 4
4 4 4 4
5 5 5 5
5 5 7 4
6 2 7 4
5 5 2 5
5 5 6 5
4 3 6 4
5 5 5 5
5 4 6 4
7 4 4 4
4 4 4 4
6 5 7 6
6 6 4 4
5 3 5 4
5 6 7 6
4 4 4 4
6 5 6 5
6 4 6 4
4 4 4 4
5 5 5 5
6 5 6 6
7 3 4 5
4 4 3 4
5 4 6 5
5 4 5 4
3 4 4 4
5 5 5 5
5 2 7 2
6 4 7 4
5 5 5 5
5 4 4 5
4 4 4 4
2 4 2 3
6 4 6 5
7 5 5 7
4 4 4 4
6 4 7 2
5 3 3 3
4 4 4 4
4 3 5 4
5 4 5 4
7 6 7 6
5 7 7 5
5 4 4 3
7 4 6 5
7 7 7 7
6 6 6 6
end

[Carlo Lazzaro]

Zach:
you may want to try:

foreach var of varlist intl* {
  2. egen sample_means`var'=mean(`var')
  3.  }

[Zach Goldberg]

Hey Carlo,

Maybe I didn't follow you correctly. But what you're suggesting simply creates a variable with a single mean of the corresponding variable. I'd like to get all 4 variable means into a single variable. Is there a way to do this?

[Clyde Schechter]

It's not clear what you want here. Do you want a single variable that, in each observation, contains the mean of the values of the four variables intlwhts intlblks intlasns intlhsps in that observation? If so, that is

egen wanted = rowmean(intlwhts intlblks intlasns intlhsps)

If that's not it, please post back with a new -dataex- example including the hand-calculated results you are looking for in a small number of observations so we can figure out what you mean.

[Zach Goldberg]

Hey Clyde,

As I mentioned in my initial post, I don't want a variable that averages the scores of the 4 variables. Rather, I want a variable that stores the individual means (thus 4 in total) of each variable. When tabulating this variable, I should get a 4-row table that lists the means of each of these variables:

In other words, I want the information in the first column (Mean) in the table above stored in a single variable. Is that possible?

[Jean-Claude Arbaut]

I'm not sure I understand why you would want to do that, but here is a way.

tabstat intlwhts intlblks intlasns intlhsps, s(mean) save
mat a=r(StatTotal)'
svmat a, n("means")
ren means1 means

If the goal is simply to reuse the means in further computations, notice that once they are stored in a matrix you can do whatever you want with the values, no need to store them in a dataset variable.

Also, there will be many missing values in this variable. To list only the means you need:

list means in f/4

HTH

Jean-Claude Arbaut

[daniel klein]

Also, there will be many missing values in this variable. To list only the means you need:

Not only will there be many missing values; the values that are not missing will have no meaningful relation to any other variable in the dataset, whatsoever. This approach seems like spreadsheet-like thinking and it is likely to cause trouble in Stata. Zach should reconsider why he wants to do this. Perhaps this is some sort of XY Problem?

Best
Daniel

[Jean-Claude Arbaut]

daniel klein

Probably not the problem here, but there is one case that would likely require this hack: plots.
I don't think it's easy to plot data from different datasets in Stata, and putting data in a single dataset is (I believe) a common way to achieve this.

Jean-Claude Arbaut