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# Re: st: tabstatmat question

 From "Alvarez,Sergio" <[email protected]> To <[email protected]> Subject Re: st: tabstatmat question Date Fri, 02 Sep 2011 12:35:09 -0400

```Sorry about ambiguity.

```
So I used the mean by group code to create the matrix that would store the mean values for each group, using:
```
egen byv=group(zone wave), lab
tabstat num_typ3, stat(mean) by(byv) save
tabstatmat TABLE

```
which gives me a matrix, or rather a vector, with all the values I need. The first few lines of the matrix in the output screen look like this:
```
TABLE[414,1]
num_typ3
1†1:mean  1.9822335
1†2:mean  2.6614173
1†3:mean  2.7150396
1†4:mean  3.3340782
1†5:mean  2.8161094
1†6:mean  1.1767857
2†1:mean  1.5857143
2†2:mean  2.1863208
2†3:mean   2.542777
2†4:mean  1.8849432

```
Now what I want to do is use -gen- or -egen- to create a variable that would look up the zone and wave of the corresponding observation from the matrix and insert the correct value in there. So I tried:
```
gen meancatch = TABLE[zone,wave]

```
and this gives the correct values for all observations with wave = 1, but creates missing values on the rest of the observations. I also tried:
```
gen meancatch = TABLE[byv,num_typ3]

```
and this gives me the correct value in some of the observations, but mostly missing values in the others.
```
```
So I must be doing something wrong, but can't figure out what. I guess the question is how to call the row and column numbers from the TABLE matrix?
```
Thanks again,

Sergio

On Fri, 2 Sep 2011 12:08:31 -0400, Austin Nichols wrote:
```
```Sergio <[email protected]> :
Now I have no idea what you are trying to do. For the mean by group,
egen mby=mean(num_typ3), by(zone wave)
```
but you are referring to (probably) nonexistent row and column numbers
```of a matrix in your example.

```
On Fri, Sep 2, 2011 at 10:42 AM, Alvarez,Sergio <[email protected]> wrote:
Thanks Austin and Nick for your help.  I used what Austin suggested (which is what Nick also suggested) and it worked. However, when I try to create the variable that contains the mean by group it works for some observations,
```but missing values are created for most of them.  I tried both:

gen meancatch = TABLE[zone,wave]
and
gen meancatch = TABLE[byv,num_typ3]

For the first line of code, it creates the correct value for all
```
observations where wave = 1, but not for any others.  The second line
```creates missing values at random (as far as I can tell).

I'd appreciate any tips.
```
```
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```
```
--
Sergio Alvarez
Food and Resource Economics
University of Florida
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```