. Author manuscript; available in PMC: 2012 Jul 1.

Published in final edited form as: Health Serv Outcomes Res Methodol. 2011 Jul 1;11(1-2):54–78. doi: 10.1007/s10742-011-0071-9

Table 5.

First Trimester Cigarette Smoking Effects on OFC under Alternative Model and Instrument Specifications

Model	Probit Regression Coefficient	Odds Ratio [95% CI]	1st IV condition X²/F [df]	2nd IV condition X² [df]	Exogenous Cigarettes X² [1]
Excluding OTHER_BEHAVIOR
Probit –	0.023^** (0.011)	1.26^** [1.02,1.56]
CML-IV probit – Instrument Specification 1	0.172^*** (0.046)	5.5^* [0.65,11.5]	13.88^** [6]	2.49 [5]; p=0.78	4.93^**
Two stage IV probit – Instrument Specification 1	0.190^** (0.081)	5.1^* [0.99,11.26]	2.63^** [6, 831]		4.51^**
CML-IV probit under alternative instrument specifications
Instrument Specification 2	0.181^*** (0.045)	5.88^* [0.97,9.95]	13.17^** [6]	2.04 [3]; p=0.56	5.51^**

Note: The models are based on a sample size of 856 observations. Standard errors of regression coefficients are in parentheses. The 95% confidence bounds of the odds ratio estimates are in brackets. The first IV condition column reports a chi-square test of the joint significance of the instruments in the cigarette function (degrees of freedom [df] in brackets). The second IV condition reports the over-identification chi-square test (df in brackets).

p < 0.1,

^**

p < 0.05,

^***

p < 0.01.