Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: st: Losing Observations in Logit
From
Fernando Rios Avila <[email protected]>
To
[email protected]
Subject
Re: st: Losing Observations in Logit
Date
Sat, 1 Mar 2014 09:21:31 -0500
Yes, that is why i said your groups are not mutually exclusive. For
instance, observations in zone 1 and cla_tam=1 are in group A and B.
Groups in cla_tam are in all groups.
Im not completely sure about the meaning of your variables, But making
a blind shot, i think what you need is the following
gen groupA=0
gen groupB=0
gen groupC=0
replace groupA=1 if zona==1 & cla_tam==1 & h_selec==1
replace groupB=1 if zona==1 & cla_tam==1 & h_selec==0
replace groupC=1 if zona==0 & cla_tam==1 & h_selec==0
Be sure that all observations are either in groups A B or C. If they
are not. Im guessing you dont need to use those observations at all,
but you should be able see that better since you know your data.
Fernando
On Sat, Mar 1, 2014 at 9:12 AM, Isobel Williams <[email protected]> wrote:
> Fernando,
>
> Thanks a lot for your help- in just changing the code to groupA==1 | groupB==1, I now have 15,988 observations. However shouldn't I have 46,413 observations?
> groupA= 32,187; groupB=14,226, so in a group A and group B sample I should have 32,187+14,226 =46,413
>
> I tried to make groups A, B, and C as exclusive as possible. Here is how my code, let me know what you think:
>
> //generate group A: in treatment area, eligible, and incorporated
> generate groupA=1 if zona==1
> replace groupA=1 if cla_tam==1
> replace groupA=1 if h_selec==1
> replace groupA=0 if zona==0
> replace groupA=0 if cla_tam==2
> replace groupA=0 if cla_tam==3
> replace groupA=0 if h_selec==0
> replace groupA=0 if h_selec==9
>
> ///generate group B: in treatment area, eligible, but not incorporated
> generate groupB=1 if zona==1
> replace groupB=1 if cla_tam==1
> replace groupB=1 if h_selec==0
> replace groupB=0 if zona==0
> replace groupB=0 if cla_tam==2
> replace groupB=0 if cla_tam==3
> replace groupB=0 if h_selec==1
> replace groupB=0 if h_selec==9
>
> ///generate group C: not in treatment area, eligible, not incorporated
> generate groupC=1 if zona==0
> replace groupC=1 if cla_tam==1
> replace groupC=1 if h_selec==0
> replace groupC=0 if zona==1
> replace groupC=0 if cla_tam==2
> replace groupC=0 if cla_tam==3
> replace groupC=0 if h_selec==1
> replace groupC=0 if h_selec==9
>
> Thanks,
> Isobel Williams
>
> ----------------------------------------
>> Date: Sat, 1 Mar 2014 08:57:10 -0500
>> Subject: Re: st: Losing Observations in Logit
>> From: [email protected]
>> To: [email protected]
>>
>> Hi Isobel,
>> I think there are two main problems with your coding.
>> First, your sample condition says:
>> keep if groupA==1 & groupB==1
>> But should say:
>> keep if groupA==1 | groupB==1
>> Since you want observations from both groups, (one or the other)
>> The second problem I see, based on your previous mail, is that groups
>> A, B and C should be mutually exclusive. Then again, perhaps the
>> definition of treatment and groups are not connected.
>> Fernando
>>
>>
>>
>> On Sat, Mar 1, 2014 at 8:48 AM, Isobel Williams <[email protected]> wrote:
>>> Dear All,
>>>
>>> I am running a logistic regression, and then pairing them using propensity score matching. Within the dataset, I have divided the data into groups A, B, and C:
>>>
>>> generate groupA=1 if zona==1
>>> replace groupA=1 if cla_tam==1
>>> replace groupA=1 if h_selec==1
>>> replace groupA=0 if zona==0
>>> replace groupA=0 if cla_tam==2
>>> replace groupA=0 if cla_tam==3
>>> replace groupA=0 if h_selec==0
>>> replace groupA=0 if h_selec==9
>>>
>>>
>>> generate groupB=1 if zona==1
>>> replace groupB=1 if cla_tam==1
>>> replace groupB=1 if h_selec==0
>>> replace groupB=0 if zona==0
>>> replace groupB=0 if cla_tam==2
>>> replace groupB=0 if cla_tam==3
>>> replace groupB=0 if h_selec==1
>>> replace groupB=0 if h_selec==9
>>>
>>> generate groupC=1 if zona==0
>>> replace groupC=1 if cla_tam==1
>>> replace groupC=1 if h_selec==0
>>> replace groupC=0 if zona==1
>>> replace groupC=0 if cla_tam==2
>>> replace groupC=0 if cla_tam==3
>>> replace groupC=0 if h_selec==1
>>> replace groupC=0 if h_selec==9
>>>
>>> when I run the tab command for all groups, Stata tells me that:
>>>
>>> . tab groupA
>>>
>>> groupA | Freq. Percent Cum.
>>> ------------+-----------------------------------
>>> 0 | 45,316 58.47 58.47
>>> 1 | 32,187 41.53 100.00
>>> ------------+-----------------------------------
>>> Total | 77,503 100.00
>>>
>>> . tab groupB
>>>
>>> groupB | Freq. Percent Cum.
>>> ------------+-----------------------------------
>>> 0 | 63,277 81.64 81.64
>>> 1 | 14,226 18.36 100.00
>>> ------------+-----------------------------------
>>> Total | 77,503 100.00
>>>
>>>
>>> . tab groupC
>>>
>>> groupC | Freq. Percent Cum.
>>> ------------+-----------------------------------
>>> 0 | 56,780 73.26 73.26
>>> 1 | 20,723 26.74 100.00
>>> ------------+-----------------------------------
>>> Total | 77,503 100.00
>>>
>>>
>>> However, when I run a logistic regression on propensity score matching between groups A and B, Stata tells me that I only have 7099 observations.
>>>
>>> Furthermore, when I wrote the code for keep if, the programme says "63227 observations deleted".
>>>
>>> Here is what I tried to do in estimating a logit propensity score and match (nearest neighbor) between groups A & B:
>>>
>>> preserve
>>> keep if groupA==1 & groupB==1
>>> logit treat floor fmiss wall hhinc2....
>>> predict double ps1
>>> psmatch2 treat, outcome (S06A20) pscore (ps1) caliper(0.2) common logit
>>> restore
>>>
>>> The objective is to estimate a logit/propensity score and match observations from group A with group B. Any help on this matter would be very much appreciated.
>>>
>>> Many thanks,
>>> Isobel Williams
>>> *
>>> * For searches and help try:
>>> * http://www.stata.com/help.cgi?search
>>> * http://www.stata.com/support/faqs/resources/statalist-faq/
>>> * http://www.ats.ucla.edu/stat/stata/
>> *
>> * For searches and help try:
>> * http://www.stata.com/help.cgi?search
>> * http://www.stata.com/support/faqs/resources/statalist-faq/
>> * http://www.ats.ucla.edu/stat/stata/
> *
> * For searches and help try:
> * http://www.stata.com/help.cgi?search
> * http://www.stata.com/support/faqs/resources/statalist-faq/
> * http://www.ats.ucla.edu/stat/stata/
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/faqs/resources/statalist-faq/
* http://www.ats.ucla.edu/stat/stata/