Error after -cem- command (coarsened exact matching)

[Navid Asgari]

Hi all,

Using Stata 17, I am trying to run coarsened exact matching commands (i.e., -cem-) introduced in this Stata Journal article: https://www.stata-journal.com/articl...article=st0176

Please note that the article's data file cannot be opened using the suggested URL. I found this public data ( lalonde_data.dta ) somewhere on the net and attached it here.

There are multiple troubles with this command. But the main issue is that after I run the following command (from the journal article):

cem age education black nodegree re74, treatment(treated)

I get this error:

cemStata(): 3001 expected 8 arguments but received 7
<istmt>: - function returned error

This issue is raised in an old thread: https://www.statalist.org/forums/for...lems-using-cem

But, it is not clear how it is resolved. Does anyone know a way around this issue? Is there an official command for CEM in Stata? I hope Stata can solve this issue by adding a properly vetted command.

Thanks,
Navid

[Scott Merryman]

After installing version 1.4 (July 2020) it works:

. net from https://www.mattblackwell.org/files/stata
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
https://www.mattblackwell.org/files/stata/
cem: Software for Coarsened Exact Matching
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Version 1.4.0 (July 27, 2020)

Matthew Blackwell, Harvard University
Stefano Iacus, University of Milan
Gary King, Harvard University
Giuseppe Porro, University of Trieste

For a brief description of cem, type net describe cem
To download documentation to your working directory, type net get cem
To install cem program files, type type net install cem


PACKAGES you could -net describe-:
    cem               Software for Coarsened Exact Matching
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

. use "C:\Users\scott\Desktop\test\lalonde_data.dta", clear
(Written by R.              )

. cem age education black nodegree re74, treatment(treated)

Matching Summary:
-----------------
Number of strata: 205
Number of matched strata: 67

             0    1
      All  425  297
  Matched  324  228
Unmatched  101   69


Multivariate L1 distance: .46113967

Univariate imbalance:

                 L1      mean       min       25%       50%       75%       max
      age    .13641   -.17634         0         0         0         0        -1
education    .00687    .00687         0         0         0         0         0
    black   3.2e-16  -2.2e-16         0         0         0         0         0
 nodegree   5.8e-16   4.4e-16         0         0         0         0         0
     re74    .06787    34.438         0         0    492.23    39.425    96.881

[Navid Asgari]

Thanks, Scott! This solved the problem.