# Displaying first stage statistics of ivreg2 using estout in Stata

I am trying to add the first stage statistics from the command `ivreg2`

, namely AP F stat, to the output for the first stage results using `estout`

. I know that these statistics are stored in the matrix `e(first)`

from the second stage, but I am having a hard time figuring out how to represent these statistics in the results of the first stage. I tried the following and didn't work:

```
ivreg2 y `included' (q=z), first ffirst savefirst savefprefix(first_)
estimates store m1
estadd matrix first=first: first_q
estimates restore first_q
```

and then tried to include `APF`

as statistics in `estout`

and it doesn't work. I also tried adding the lines:

```
matrix first=e(first)
estadd scalar APF=first[7,1]
```

and that doesn't work either. I also tried to write a new subcommand `_estadd_apf.ado`

and couldn't get it to work, and tried using the syntax `myel[#]`

described in the help file `estout`

and that won't work either. (It looks like including parentheses anywhere in the parameter `stats()`

results in an error.) I also tried the `aux()`

wrapped parameter `esttab`

and it didn't work.

When I type `matrix list first`

I can see the correct APF value, but it is stored in a matrix, not a scalar, and `estout`

will not include it in the table, the cells are just empty. I also tried to just define a local scalar without using it `estadd`

, and that won't work either. Any suggestions?

source to share

Am I missing something? `estadd scalar`

seems to work in this case.

```
clear
set more off
use http://fmwww.bc.edu/ec-p/data/hayashi/griliches76.dta // example from the help file
xi i.year
ivreg2 lw s expr tenure rns smsa _I* (iq=med kww age mrt), small first ffirst savefirst savefprefix(first_)
mat first=e(first)
estadd scalar APF=first[7,1]
estout, c(b) stats(APF)
```

source to share