Hi, I am using Stata 13 to analyse some observational data and a treatment. I came across an abundance of possible ways to estimate treatment effects with Stata. Let me just show you two options below (excluding the popular psmatch2, pscore and attn etc.).
I use the Cattaneo sample, which offers some material on the mother's habit to smoke (treatment), birth weight of a child (endogenous variable), and a few factors to match (here randomly selected marriage status of the mother, mother's age, and first baby). I always calculate the average treatment effect on the treated and match at least one nearest neighbour.
I tried to specify the commands as similar as possible - but the outcomes differ a bit: -245.711 vs. -239.2433.
I have a few questions: First and foremost, why do the results differ? When should one use psmatch and when nnmatch? And, why can I specify nnmatch to exactly match on some criteria (via
ematch) and why is that not the case for psmatch?
Crosspost Cross Validated: http://stats.stackexchange.com/quest...t364219_191733
Recent post: In a simialr vein, I posted a related question at Statalist here: http://www.statalist.org/forums/foru...der-conditions
Code:
use "http://www.stata-press.com/data/r13/cattaneo2.dta", clear global treat mbsmoke global match mmarried mage medu fbaby global ylist bweight *Option 1: teffects psmatch teffects psmatch ($ylist) ($treat $match, logit), atet *Option 2: teffects nnmatch teffects nnmatch ($ylist $match) ($treat), atet
I tried to specify the commands as similar as possible - but the outcomes differ a bit: -245.711 vs. -239.2433.
I have a few questions: First and foremost, why do the results differ? When should one use psmatch and when nnmatch? And, why can I specify nnmatch to exactly match on some criteria (via
ematch) and why is that not the case for psmatch?
Crosspost Cross Validated: http://stats.stackexchange.com/quest...t364219_191733
Recent post: In a simialr vein, I posted a related question at Statalist here: http://www.statalist.org/forums/foru...der-conditions