parentheses unbalanced for reghdfe

[Roxanna Sh]

Hi all,
I want to do instrumental variable analysis using reghdfe. My syntax perfectly worked with Stata 17 but now with Stata 18 it gives me the parentheses unbalanced error. I could not find any online resources to fix the issue. Any help would appreciated. Here is my syntax

reghdfe profit firm_age firm size i.year (ab =instrument), absorb(firmid) vce (cluster firmid) old stage (first)

[Andrew Musau]

I'm not sure there was ever a version of reghdfe that supported IV regression. Are you perhaps thinking of ivreghdfe? If you don't have it, you can install it from https://github.com/sergiocorreia/ivreghdfe.

[Felix Bittmann]

Under 7.4, the website states:

The IV functionality of reghdfe has been moved into ivreghdfe.

https://scorreia.com/help/reghdfe.html

So I guess maybe you have used quite old syntax. Switching to ivreghdfe will resolve the issue.

[Andrew Musau]

Under 7.4, the website states:

The IV functionality of reghdfe has been moved into ivreghdfe.

That being the case, one could use the -version()- option of reghdfe to run an IV regression. However, I still recommend using ivreghdfe, as the old version may contain bugs that were fixed in later updates. The following works for me:

webuse nlswork, clear
reghdfe ln_w age c.age#c.age not_smsa (tenure = union south), absorb(id) version(3)

Res.:

. reghdfe ln_w age c.age#c.age not_smsa (tenure = union south), absorb(id) version(3)
(running historical version of reghdfe: 3)
(dropped 673 singleton observations)
(converged in 1 iterations)

HDFE IV (2SLS) estimation
-------------------------

Estimates efficient for homoskedasticity only
Statistics consistent for homoskedasticity only

                                                      Number of obs =    18334
                                                      F(  4, 14869) =    74.14
                                                      Prob > F      =   0.0000
Total (centered) SS     =  1119.473248                Centered R2   =  -0.4975
Total (uncentered) SS   =  1119.473248                Uncentered R2 =        .
Residual SS             =  5907.007821                Root MSE      =    .6303

------------------------------------------------------------------------------
     ln_wage | Coefficient  Std. err.      t    P>|t|     [95% conf. interval]
-------------+----------------------------------------------------------------
      tenure |   .2403531   .0373419     6.44   0.000     .1671583    .3135478
         age |   .0118437   .0090032     1.32   0.188    -.0058037    .0294912
             |
 c.age#c.age |  -.0012145   .0001968    -6.17   0.000    -.0016003   -.0008286
             |
    not_smsa |  -.0167178   .0339236    -0.49   0.622    -.0832123    .0497767
------------------------------------------------------------------------------
Underidentification test (Anderson canon. corr. LM statistic):          52.345
                                                   Chi-sq(2) P-val =    0.0000
------------------------------------------------------------------------------
Weak identification test (Cragg-Donald Wald F statistic):               21.286
Stock-Yogo weak ID test critical values: 10% maximal IV size             19.93
                                         15% maximal IV size             11.59
                                         20% maximal IV size              8.75
                                         25% maximal IV size              7.25
Source: Stock-Yogo (2005).  Reproduced by permission.
------------------------------------------------------------------------------
Sargan statistic (overidentification test of all instruments):           1.691
                                                   Chi-sq(1) P-val =    0.1935
------------------------------------------------------------------------------
Instrumented:         tenure
Included instruments: age c.age#c.age not_smsa
Excluded instruments: union south
------------------------------------------------------------------------------

Absorbed degrees of freedom:
---------------------------------------------------------------+
 Absorbed FE |  Num. Coefs.  =   Categories  -   Redundant     | 
-------------+-------------------------------------------------|
      idcode |         3461            3461              0     | 
---------------------------------------------------------------+

.