RE: Re: st: Balancing Property not satisfied

["Ariel Linden, DrPH" <ariel.linden@gmail.com>]

Vikram,

Have you created a table of baseline characteristics between your two groups
to see if there is overlap on those observed characteristics? Have you
performed some visual checks of their distributions, such as QQ-plots,
box-plots, density plots, etc.? 

If your covariates don't balance, it is likely that you don't have
sufficient overlap in the distributions, thus, any analysis you'd perform
would be resorting to extrapolation. Take for example two groups with no
overlap in age. No amount of matching will get these groups to look
comparable. If age is an independent predictor of the outcome, you'll have
problems making the case that you've controlled for age.

Since you did not share with us any tables or output, that is about as much
of a response as I can offer you...

There is no substitute for conducting basic analysis of the data to inform
the researcher where to go next.

 Ariel

Date: Thu, 15 Aug 2013 21:53:43 +0100
From: V!cky Finavker <vikramfinavker@gmail.com>
Subject: Re: st: Balancing Property not satisfied

Hi Lukas,

Thanks for you help. However, when i change those covariates Pscore shows
another covariates as having balancing problem. so do i have to keep on
trying until i find one which satisfies or there is a solution?
______
Regards,

Vikram Finavker






On 15 Aug 2013, at 12:03, Lukas Borkowski <570722@soas.ac.uk> wrote:

> Vikram,
> 
> in the output window of -pscore- (a user-written command, written by
Becker and Ichino, 2002) you are provided with information on which
covariates are not balanced. It is written just above the dialogue you have
quoted.
> 
> Best,
> 
> Lukas
> Becker, S. and A. Ichino (2002): Estimation of average treatment effects
based on propensity scores, The Stata Journal 2(4): pp. 358-377.
> 
> #


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