Hello,
I am looking for some support regarding multichotomous treatment
variables with cem ( in stata). I have seen various references that
mention that cem supports this type of treatment, though results
suggest that cem cannot compute distances and weights when this is the
case. Will cem be updated to support this type of analysis?
--
With best wishes,
Lindsay
Lindsay M. Pettingill
Ph.D. Student, Government
Georgetown University
Washington, DC 20057
http://government.georgetown.edu/graduatestudents/lmp67/
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Thanks; this is useful.
________________________________________
From: Ariel Linden, DrPH [ariel.linden(a)gmail.com]
Sent: Wednesday, August 24, 2011 6:16 PM
To: 'Gary King'; Nel Dutt
Cc: cem(a)lists.gking.harvard.edu
Subject: RE: [cem] Using CEM with Panel Data in Stata
I would argue that it depends on whether the analysis is intended to be longitudinal or cross-sectional. If a firm is matched to others in one year, but then matched to others in the next year, they may not be following the same trajectory over time. This may be irrelevant if the intent is to show cross-sectional results at each time interval. However, if the intent is to show the trajectory over time, perhaps it makes sense to match at the baseline (or first time interval) and then observe the trajectories over time.
Ariel
From: owner-cem_at_lists_gking_harvard_edu(a)mail.hmdc.harvard.edu [mailto:owner-cem_at_lists_gking_harvard_edu@mail.hmdc.harvard.edu] On Behalf Of Gary King
Sent: Wednesday, August 24, 2011 6:09 PM
To: Nel Dutt
Cc: cem(a)lists.gking.harvard.edu
Subject: Re: [cem] Using CEM with Panel Data in Stata
there's nothing necessarily wrong with this strategy. the only question for you is whether those matches are really sufficiently equivalent. matching different years means that for sure there will be some differences (even if only the last digit of the year!), but you're going to need to decide whether those make a difference in your analysis and the effect of that on the outcome is important enough.
Gary
--
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On Wed, Aug 24, 2011 at 5:44 PM, Nel Dutt <nilanjana.dutt(a)duke.edu<mailto:nilanjana.dutt@duke.edu>> wrote:
Hi all,
I am using CEM on a panel dataset with the k2k option. I am currently matching observations by year (and a few other covariates). I was wondering if there are any econometric problems while running regressions (post matching) with a matched sample which contains the following situation:
in year t observation_1 is matched with observation_2, but in year t+1 observation_1 is matched with observation_3. That is, in different years the same firm is matched with different firms.
Thanks,
Nel
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Hi all,
I am using CEM on a panel dataset with the k2k option. I am currently matching observations by year (and a few other covariates). I was wondering if there are any econometric problems while running regressions (post matching) with a matched sample which contains the following situation:
in year t observation_1 is matched with observation_2, but in year t+1 observation_1 is matched with observation_3. That is, in different years the same firm is matched with different firms.
Thanks,
Nel
Hello-
I have been trying to install CEM for SPSS 19. I followed every installation
step and I think it was successfully installed. But when I run the program,
it gives me the error messages as below:
GET
FILE='E:\Users\Michiko\Desktop\lalonde.sav'.
>Warning. Command name: GET FILE
>SPSS Statistics data file "E:\Users\Michiko\Desktop\lalonde.sav" is written
in a character encoding (ISO_8859-1:1987)
>incompatible with the current LOCALE setting. It may not be readable.
>Consider changing LOCALE or setting UNICODE on. (DATA 1721)
DATASET NAME DataSet1 WINDOW=FRONT.
CEM TREATMENT=treated VARIABLES=age education black married nodegree re74
re75.
>Error # 6887. Command name: BEGIN PROGRAM
>External program failed during initialization.
>Execution of this command stops.
Additional error message: Load Python library failed.
>Error # 6887. Command name: BEGIN PROGRAM
>External program failed during initialization.
FREQUENCIES VARIABLES=age
/ORDER=ANALYSIS.
I also followed the instuction for troubleshooting (
http://projects.iq.harvard.edu/cem-spss/pages/troubleshooting) so I got no
error message on R, so I should be okay on this one.. Can someone please
help me figure out what I need to do to successfuly run CEM on SPSS?
Thank you!
Michiko Clutter
--
Michiko Otsuki Clutter, PhD
Assistant Professor in Psychology
University of South Florida, St. Petersburg
140 7th Avenue South, Davis Hall 258
St. Petersburg, FL 33701
(TEL) 727-873-4867
Hello list,
I am having troubles getting cem to run (imb works fine). Any code I do
with cem returns this error message:
. cem
invalid syntax
r(197);
whether I include variables, the treatment variable or not. I installed
via ssc:
. ssc install cem
checking cem consistency and verifying not already installed...
all files already exist and are up to date.
I am really puzzled as to why, as imb works. I assume there must be a
problem with the cem ado file, as shouldn't it return the "valist
required" if I only call the command "cem" (without anything)? Any help
would be greatly appreciated!
I am running Stata 10 (fully updated), Linux-32bit. Would you need any
more information than that?
Thanks a lot for your time and help,
Christoph
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Hi,
When I type library(cem), cem appears to load, but I am, unable to execute
any commands in R afterwards. I've pasted in the commands I've used and what
R has printed in the log. It seems like there's an error, but I don't
understand what's going on. (I've gotten this rrot on my Mac Pro with 20GB
ram and my macbook air.) Any help greatly appreciated. Thanks, Bill
[R.app GUI 1.40 (5751) x86_64-apple-darwin9.8.0]
[History restored from /Users/undefined/.Rapp.history]
> library(cem)
Loading required package: nlme
Loading required package: lattice
Loading required package: randomForest
randomForest 4.6-2
Type rfNews() to see new features/changes/bug fixes.
Loading required package: tcltk
Loading Tcl/Tk interface ...
*** caught segfault ***
address 0x1000080, cause 'memory not mapped'
Traceback:
1: sys.parent()
2: sys.function(sys.parent())
3: formals(sys.function(sys.parent()))
4: match.arg(encoding)
5: match(match.arg(encoding), c("", "bytes", "UTF-8"))
6: textConnection("rval", "w", local = TRUE)
7: capture.output(print(args(load)))
8: paste(capture.output(print(args(load))), collapse = "")
9: gsub("\\s+", " ", paste(capture.output(print(args(load))), collapse =
""))
10: doTryCatch(return(expr), name, parentenv, handler)
11: tryCatchOne(expr, names, parentenv, handlers[[1L]])
12: tryCatchList(expr, classes, parentenv, handlers)
13: tryCatch(expr, error = function(e) { call <- conditionCall(e) if
(!is.null(call)) { if (identical(call[[1L]], quote(doTryCatch)))
call <- sys.call(-4L) dcall <- deparse(call)[1L]
prefix <- paste("Error in", dcall, ": ") LONG <- 75L msg <-
conditionMessage(e) sm <- strsplit(msg, "\n")[[1L]] w <- 14L +
nchar(dcall, type = "w") + nchar(sm[1L], type = "w") if (is.na(w))
w <- 14L + nchar(dcall, type = "b") + nchar(sm[1L],
type = "b") if (w > LONG) prefix <- paste(prefix, "\n
", sep = "") } else prefix <- "Error : " msg <- paste(prefix,
conditionMessage(e), "\n", sep = "") .Internal(seterrmessage(msg[1L]))
if (!silent && identical(getOption("show.error.messages"), TRUE)) {
cat(msg, file = stderr()) .Internal(printDeferredWarnings())
} invisible(structure(msg, class = "try-error"))})
14: try(gsub("\\s+", " ", paste(capture.output(print(args(load))),
collapse = "")), silent = TRUE)
Possible actions:
1: abort (with core dump, if enabled)
2: normal R exit
3: exit R without saving workspace
4: exit R saving workspace
> load()
Selection:
Dear CEM list -
After running the CEM, the cem_matched variable indicates that 100,552
(97,161 controls to 3,391 treatment) of my observations are matched.
However, of these, 86,261 or 85%, are missing the cem_strata variable.
I quickly looked through the data and cem_weights have been attached as
well.
Any potential suggestions as to what is going on?
Many Thanks,
Ethan
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Dear CEM list,
I am using CEM to match individuals receiving workers compensation from
an injury to non-injured workers. We have several continuous variables
(e.g., income, firm size, age), a categorical variable (e.g., industry)
as well as some dichotomous variables (e.g., gender, born in state).
The sample is quite large with many more potential controls (1.2
million) than injured workers (4 thousand). Prior to using CEM I
coarsened the data myself by putting income into quintiles, four firm
size categories, 4 age groups, and 10 industry categories. I then ran
CEM with automatic cuts. However, based upon the sample size Stuge's
Rule creates 22 bins for each variable which in many cases don't exist
(1/2 a woman). The bins tend not to be very "coarse" with approximately
2,000 strata.
To try and improve this, I put in some cut points similar (coarser than
above mention) and then the program never seemed to finish running (2
days later I killed it).
Thus, I am thinking of using a different set of auto cuts, but I think
the Freedman-Diaconis rule would yield even more cutpoints and I wasn't
sure what other algorithms were available (none listed in the Stata
Journal Article).
Do you have any suggestion how to coarsen the data further so that I can
get the most out of the program?
Thanks in advance for your help!
Ethan Scherer MPP, CPA
Doctoral Fellow, Pardee RAND Graduate School
1776 Main St., Mailstop M1N
Santa Monica, CA 90401
W: 310-393-0411 x6056
E: escherer(a)rand.org
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Hi, cemers,
I am currently using cem to examine whether domestic firms being geographically close to foreign firms affects their exports (the geogrpahical proximity is the treatment). After cem (over a set of firm characteristics, such as firm size), I obtained the imabalance indicator:
Multivariate L1 distance: 1.9969533
However, the manual says that L1 shall be between 0 and 1. Can anybody help?
Cheers
Sun
Dr Sizhong Sun
Lecturer in Economics
School of Business, James Cook University, QLD 4814
P (07) 4781 4710
I +61 7 4781 4710
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Dear all,
Hope all is well. I have an installation question. I tried to install CEM in Stata using instructions on the website. The first set of instructions did not work (net install cem). The second set of instructions did work, but then it said cemStata() not found. I'm guessing this means something is missing from the installation package, rather than anything on my end, given that I just typed in the commands as given. Or do I need to download something else?
net from http://gking.harvard.edu/cem/
file http://gking.harvard.edu/cem/stata.toc not found
http://gking.harvard.edu/cem/ either
1) is not a valid URL, or
2) could not be contacted, or
3) is not a Stata download site (has no stata.toc file).
r(601);
. net install cem
file http://www.stata.com/cem.pkg not found
server says file temporarily redirected to http://www.stata.com/error/404.html
could not load cem.pkg from http://www.stata.com/
r(601);
. ssc install cem
checking cem consistency and verifying not already installed...
installing into /Users/janet/Library/Application Support/Stata/ado/stbplus/...
installation complete.
. cem x1 x2, treatment(y) autocuts(fd)
<istmt>: 3499 cemStata() not found
r(3499);
. cem x1, treatment(y) autocuts(fd)
<istmt>: 3499 cemStata() not found
r(3499);
Thanks for your help,
Janet
Janet Rosenbaum
Assistant Professor, Department of Behavioral and Community Health
University of Maryland School of Public Health, College Park.
jerosenb(a)umd.edu
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