________________________________ From: Gary King <king(a)harvard.edu> To: Ana Kolar <annakolar(a)yahoo.com> Cc: "matchit(a)lists.gking.harvard.edu" <matchit(a)lists.gking.harvard.edu> Sent: Wednesday, 3 August 2011, 22:22 Subject: Re: [matchit] getting a matrix of matched pairs Cem has a pair() function to do this. Gary King http://gking.harvard.edu 617-500-7570 (from my phone) On Aug 3, 2011 1:54 AM, "Ana Kolar" <annakolar(a)yahoo.com> wrote:

cbind(lalonde[row.names(foo$match.matrix),"re78"], lalonde[foo$match.matrix,"re78"])

________________________________ From: Geoffrey Smith <gps(a)asu.edu> To: Ana Kolar <annakolar(a)yahoo.com> Cc: Gary King <king(a)harvard.edu>du>; "matchit(a)lists.gking.harvard.edu" <matchit(a)lists.gking.harvard.edu> Sent: Wednesday, 3 August 2011, 22:46 Subject: Re: [matchit] getting a matrix of matched pairs See section 5.5 of the .pdf version of the manual available at http://gking.harvard.edu/matchit .  Geoff On Wed, Aug 3, 2011 at 1:36 PM, Ana Kolar <annakolar(a)yahoo.com> wrote: If I understand this correctly. While using matchit function, we can get matched pairs only if "cem" method is used and there is no option to get matched pairs if we use other methods like "nearest", "optimal", "full" or "genetic"? -- Geoffrey Smith Visiting Assistant Professor

________________________________ From: Kosuke Imai <kimai(a)Princeton.EDU> To: Ana Kolar <annakolar(a)yahoo.com> Cc: "matchit(a)lists.gking.harvard.edu" <matchit(a)lists.gking.harvard.edu> Sent: Wednesday, 3 August 2011, 23:02 Subject: Re: [matchit] getting a matrix of matched pairs That's an example code. You would have to replace "foo" etc with your own objects.  Kosuke Imai Princeton University http://imai.princeton.edu

On Aug 3, 2011, at 4:56 PM, "Ana Kolar" <annakolar(a)yahoo.com> wrote: Thank you Geoff, but this line of code unfortunately doesnt work. Object 'foo' is not found. No idea what that object 'foo' actually means. Could you please give an advice on that?

cbind(lalonde[row.names(m.out$match.matrix),"re78"], lalonde[m.out$match.matrix,"re78"])

m.out

________________________________ From: Kosuke Imai <kimai(a)Princeton.EDU> To: Ana Kolar <annakolar(a)yahoo.com> Cc: "matchit(a)lists.gking.harvard.edu" <matchit(a)lists.gking.harvard.edu> Sent: Wednesday, 3 August 2011, 23:10 Subject: Re: [matchit] getting a matrix of matched pairs It's the output object from matchit() command.  Kosuke Imai Princeton University http://imai.princeton.edu

On Aug 3, 2011, at 5:07 PM, "Ana Kolar" <annakolar(a)yahoo.com> wrote: I believe so, but this example code doesn't work on the lalonde example that you have provided throughout the package. Could you please point me towards what that 'foo' object represents? Ana > > > >>________________________________ >> From: Kosuke Imai <kimai(a)Princeton.EDU> >>To: Ana Kolar <annakolar(a)yahoo.com> >>Cc: "matchit(a)lists.gking.harvard.edu" <matchit(a)lists.gking.harvard.edu> >>Sent: Wednesday, 3 August 2011, 23:02 >>Subject: Re: [matchit] getting a matrix of matched pairs >> >> >>That's an example code. You would have to replace "foo" etc with your own objects.  >> >> >>Kosuke Imai >>Princeton University >>http://imai.princeton.edu >> >>

Hi Ana, The code works fine if you do nearest neighbor matching, for which the match.matrix makes sense: married + + nodegree + re74 + re75, data = lalonde, method = "nearest") lalonde[m.out$match.matrix,"re78"]) [,1] [,2] [1,] 9930.0460 959.04450 [2,] 3595.8940 6847.78500 [3,] 24909.4500 2231.36700 [4,] 7506.1460 2281.61000 [5,] 289.7899 0.00000 [6,] 4056.4940 17833.20000 If you are using cem it sounds from Gary’s email like the “pair” function is the way to get similar information. Liz On 8/3/11 5:16 PM, "Ana Kolar" &lt;annakolar(a)yahoo.com&gt; wrote: I believe that the output object of matchit is called m.out (in your example). And unfortunately it doesn't work or am I doing something wrong? Please look at the example below. lalonde[m.out$match.matrix,"re78"]) [,1] [,2] Call: matchit(formula = treat ~ age + educ + black + hispan + married + nodegree + re74 + re75, data = lalonde, method = "cem") Control Treated All 429 185 Matched 78 68 Unmatched 351 117 Discarded 0 0 ------------------------------------------------------------------------ *From:*Kosuke Imai &lt;kimai(a)Princeton.EDU&gt; *To:* Ana Kolar &lt;annakolar(a)yahoo.com&gt; *Cc:* &quot;matchit(a)lists.gking.harvard.edu&quot; &lt;matchit(a)lists.gking.harvard.edu&gt; *Sent:* Wednesday, 3 August 2011, 23:10 *Subject:* Re: [matchit] getting a matrix of matched pairs It's the output object from matchit() command. Kosuke Imai Princeton University http://imai.princeton.edu Sent from my iPhone On Aug 3, 2011, at 5:07 PM, "Ana Kolar" &lt;annakolar(a)yahoo.com&gt; wrote: I believe so, but this example code doesn't work on the lalonde example that you have provided throughout the package. Could you please point me towards what that 'foo' object represents? Ana ------------------------------------------------------------------------ *From:*Kosuke Imai &lt;kimai(a)Princeton.EDU&gt; *To:* Ana Kolar &lt;annakolar(a)yahoo.com&gt; *Cc:* &quot;matchit(a)lists.gking.harvard.edu&quot; &lt;matchit(a)lists.gking.harvard.edu&gt; *Sent:* Wednesday, 3 August 2011, 23:02 *Subject:* Re: [matchit] getting a matrix of matched pairs That's an example code. You would have to replace "foo" etc with your own objects. Kosuke Imai Princeton University <http://imai.princeton.edu> http://imai.princeton.edu Sent from my iPhone On Aug 3, 2011, at 4:56 PM, "Ana Kolar" < <mailto:annakolar@yahoo.com> annakolar(a)yahoo.com&gt; wrote: Thank you Geoff, but this line of code unfortunately doesnt work. Object 'foo' is not found. No idea what that object 'foo' actually means. Could you please give an advice on that? lalonde[foo$match.matrix,"re78"]) Error in row.names(foo$match.matrix) : object 'foo' not found ------------------------------------------------------------------------ *From:*Geoffrey Smith < <mailto:gps@asu.edu> gps(a)asu.edu&gt; *To:* Ana Kolar < <mailto:annakolar@yahoo.com> annakolar(a)yahoo.com&gt; *Cc:* Gary King < <mailto:king@harvard.edu> king(a)harvard.edu&gt;gt;; " <mailto:matchit@lists.gking.harvard.edu> matchit(a)lists.gking.harvard.edu&quot; < <mailto:matchit@lists.gking.harvard.edu> matchit(a)lists.gking.harvard.edu&gt; *Sent:* Wednesday, 3 August 2011, 22:46 *Subject:* Re: [matchit] getting a matrix of matched pairs See section 5.5 of the .pdf version of the manual available at <http://gking.harvard.edu/matchit> <http://gking.harvard.edu/matchit> http://gking.harvard.edu/matchit . Geoff On Wed, Aug 3, 2011 at 1:36 PM, Ana Kolar < <mailto:annakolar@yahoo.com> <mailto:annakolar@yahoo.com> annakolar(a)yahoo.com&gt; wrote: If I understand this correctly. While using *matchit *function, we can get matched pairs only if "cem" method is used and there is no option to get matched pairs if we use other methods like "nearest", "optimal", "full" or "genetic"? ------------------------------------------------------------------------ *From:*Gary King < <mailto:king@harvard.edu> <mailto:king@harvard.edu> king(a)harvard.edu&gt; *To:* Ana Kolar < <mailto:annakolar@yahoo.com> <mailto:annakolar@yahoo.com> annakolar(a)yahoo.com&gt; *Cc:* " <mailto:matchit@lists.gking.harvard.edu> <mailto:matchit@lists.gking.harvard.edu> matchit(a)lists.gking.harvard.edu&quot; < <mailto:matchit@lists.gking.harvard.edu> <mailto:matchit@lists.gking.harvard.edu> matchit(a)lists.gking.harvard.edu&gt; *Sent:* Wednesday, 3 August 2011, 22:22 *Subject:* Re: [matchit] getting a matrix of matched pairs Cem has a pair() function to do this. Gary King <http://gking.harvard.edu> <http://gking.harvard.edu> http://gking.harvard.edu 617-500-7570 (from my phone) On Aug 3, 2011 1:54 AM, "Ana Kolar" < <mailto:annakolar@yahoo.com> <mailto:annakolar@yahoo.com> annakolar(a)yahoo.com&gt; wrote: pairs? The thing is that when match.data function is used, we only get all the data that are matched, while I would be more interested in getting the matched pairs.