Thanks, but I’m still encountering problems.
I ran this code:
use "D:\Documents\Midura Paquette\6.16.14 NCDB - Rectal CA only.dta", clear
generate approach1 = 1
replace approach1 = 2 if approach == "open"
replace approach1 = 3 if approach == "laparoscopic"
generate margins1 = 1
replace margins1 = 0 if margins == "negative"
drop if approach1 == .
summarize margins1 age approach1
logistic margins1 i.approach1
cem margins1 age, tr(approach1)
and got this output:
. do "C:\Users\Hanseman\AppData\Local\Temp\STD00000000.tmp"
. use "D:\Documents\Midura Paquette\6.16.14 NCDB - Rectal CA only.dta", clear
.
. generate approach1 = 1
. replace approach1 = 2 if approach == "open"
(6352 real changes made)
. replace approach1 = 3 if approach == "laparoscopic"
(2444 real changes made)
.
. generate margins1 = 1
. replace margins1 = 0 if margins == "negative"
(8512 real changes made)
.
. drop if approach1 == .
(0 observations deleted)
. summarize margins1 age approach1
Variable | Obs Mean Std. Dev. Min Max
-------------+------------------------------------------------------------------------
margins1 | 9253 .0800821 .271435 0 1
age | 9253 62.45888 13.09845 18 90
approach1 | 9253 2.214741 .5171413 1 3
. logistic margins1 i.approach1
Logistic regression Number of obs = 9253
LR chi2(2) = 21.80
Prob > chi2 = 0.0000
Log likelihood = -2570.4092 Pseudo R2 = 0.0042
------------------------------------------------------------------------------
margins1 | Odds Ratio Std. Err. z P>|z| [95% Conf. Interval]
-------------+--------------------------------------------------------------------------------------------
approach1 |
2 | 1.754614 .3760161 2.62 0.009 1.152837 2.670516
3 | 1.213282 .273746 0.86 0.392 .7796687 1.88805
|
_cons | .0554273 .0116234 -13.79 0.000 .036747 .0836035
------------------------------------------------------------------------------
. cem margins1 age, tr(approach1)
Matching Summary:
-----------------
Number of strata: 28
Number of matched strata: 24
1 2 3
All 457 6352 2444
Matched 457 6292 2427
Unmatched 0 60 17
imbalance(): 3258 <tmp>[1,1] found where void required
<istmt>: - function returned error
r(3258);
end of do-file
r(3258);
.
This is a mystery to me. Do you have other ideas as to what might be going wrong.
Thanks for your help.
Dennis Hanseman
From: Matt Blackwell [mailto:mblackwell@gov.harvard.edu]
Sent: Friday, July 25, 2014 8:32 AM
To: Ariel Linden
Cc: Dennis Hanseman; cem@lists.gking.harvard.edu
Subject: Re: [cem] Error when using cem with >2 treatments
Hi Dennis,
We need to implement an "if" syntax for the imbalance command, but it's still a work in progress. For now, you can simply subset the data to non-missing treatments:
drop if approach1 != .
That should solve the error.
Cheers,
Matt
~~~~~~~~~~~
Matthew Blackwell
Assistant Professor of Government
Harvard University
On Thu, Jul 24, 2014 at 9:09 PM, Ariel Linden <ariel.linden@gmail.com> wrote:
So the matching worked, just not –imbalance- … I’ll have to Let Matt Blackwell field this error.
From: Dennis Hanseman [mailto:hanseman@one.net]
Sent: Thursday, July 24, 2014 8:51 PM
To: 'Ariel Linden'; cem@lists.gking.harvard.edu
Subject: RE: [cem] Error when using cem with >2 treatments
Tried that, but got the error message again:
. cem margins1 age if approach1 != . , tr(approach1)
Matching Summary:
-----------------
Number of strata: 28
Number of matched strata: 24
1 2 3
All 457 6352 2444
Matched 457 6292 2427
Unmatched 0 60 17
imbalance(): 3258 <tmp>[1,1] found where void required
<istmt>: - function returned error
r(3258);
Dennis
From: Ariel Linden [mailto:ariel.linden@gmail.com]
Sent: Thursday, July 24, 2014 8:09 PM
To: Dennis Hanseman; cem@lists.gking.harvard.edu
Subject: Re: [cem] Error when using cem with >2 treatments
Your "if" statement needs to come before the comma
Ariel
From: Dennis Hanseman
Sent: Thursday, July 24, 2014 8:01 PM
Subject: [cem] Error when using cem with >2 treatments
I’m trying to use cem to do matching involving 3 treatments. Prof. King (http://comments.gmane.org/gmane.comp.lang.r.matchit/393) indicated that this can be done.
When I tried it, I got an error message –
imbalance(): 3258 <tmp>[1,1] found where void required
<istmt>: - function returned error
There was a discussion on this site on July 24 of 2013 about a similar issue. In that case, there were only 2 treatments but a treatment of “.”, along with “1” and “2”, showed up in the summary table. The suggestion was to add “if indepvote != ." to the cem call.”While I’m sure that there are no missing values of my treatment variable, I still tried to add the if clause to my cem call. But it didn’t help. I got another error:. cem margins1 age, tr(approach1) if approach1 != .
option if not allowed
r(198);
Any ideas of how I can proceed?
Thanks.
Dennis Hanseman
-
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