New subject: [matchit] Ask for Help on MatchIt and Zelig, Thanks

20 Dec 2012

Dear all,

I am learning the MatchIt paper by Ho et al. in Journal of Statistical
Software (Vol. 42, No.8, 2011).
However, when I went through all the codes in this paper I met two problems
that troubled me for two days .
As a result, I need your help. Thank you very much!

In fact, all the problems once took place. Before this email, I have
checked almost all the relevant solutions (like updating the software) in
this emaillist, however it still doesn't work.

In respect to the software, I am using the most updated software, including
ZELIG (Versions 4.1-0, built: 2012-11-09) and
MatchIt (Version 2.4-20, built: 2011-10-24) and R (version 2.15.2).
Therefore, I don't think it is a problem from software.

1. In the part of estimating "Average Treatment effect on the treated", I
copy the following code into R.

x.out1 <- setx(z.out1, data = match.data(m.out1, "treat"), cond = TRUE)

However it will give a warning message as follows. Does it matter? What
order does the new Zelig support?

Warning message:
In setx.default(z.out1, data = match.data(m.out1, "treat"), cond = TRUE) :
  "cond" is not currently supported by this version of Zelig

2. When I try to estimate the Average Treatment Effect (overall), I copy
the following code.

ate.all <- c(s.out1$qi$att.ev, -s.out2$qi$att.ev)

It will indicates that "Error in -s.out2$qi$att.ev : invalid argument to
unary operator", which finally make me failing to continue.

I totally copy the codes in the article. Then what happened?

Would you like to tell me how to get rid of the failure?

Thank you very much!

Best wishes,

Mao

-- 
Mao Weizhun

Department of Politics and Management
Chair of International Politics
University of Konstanz
Room D 246
P.O. Box D 86
D-78457 Konstanz
Germany

Phone(O):+49-7531-88-4421
Email: Weizhun.Mao(a)uni-konstanz.de
Web:http://www.polver.uni-konstanz.de/gschneider/mitarbeiter/mao-weizhun/