. Author manuscript; available in PMC: 2008 Dec 10.

Published in final edited form as: J Econ Hist. 2007 Dec;67(4):1001–1035. doi: 10.1017/S0022050707000472

TABLE 4.

PROBIT REGRESSIONS: MALARIA RISK BEFORE ENLISTMENT AND SUSCEPTIBILITY TO SPECIFIC INFECTIONS DURING THE CIVIL WAR (dependent variable: dummy = 1 if the veteran contracted the disease during the Civil War)

		Diarrhea (mean = 0.2848)		Pneumonia (mean = 0.0492)		Malaria (mean = 0.1042)		Measles (mean = 0.0481)		Typhoid (mean = 0.0778)
Variables	Mean	dy/dx	z-value	dy/dx	z-value	dy/dx	z-value	dy/dx	z-value	dy/dx	z-value
Malaria risk at 1850 residence	0.1477	0.2037	3.35	0.0238	1.23	0.0994	2.48	0.0999	4.19	−0.0273	−0.79
U.S.-born	0.8744	0.0285	1.70	−0.0043	−1.11	0.0237	2.25	0.0076	1.11	0.0132	1.40
Age at enlistment	24.08	0.0001	0.18	−0.0002	−1.12	−0.0015	−3.14	−0.0026	−7.61	−0.0012	−2.94
Height at enlistment (inches)	68.05	0.0013	0.60	0.0001	0.32	−0.0017	−1.13	0.0001	0.07	0.0005	0.37
Occupation and residence before enlistment
Farmer living in rural area	0.5673	NI		NI		NI		NI		NI
Nonfarmer living in rural area	0.3915	−0.0477	−4.00	−0.0054	−1.34	−0.0020	−0.25	−0.0194	−4.04	−0.0153	−2.30
Living in urban area	0.0411	−0.0450	−1.60	−0.0027	−0.64	0.0131	0.63	−0.0283	−4.45	−0.0093	−0.58
In(total household wealth in 1850)	4.1936	−0.0009	−0.54	−0.0001	−0.55	−0.0003	−0.26	0.0003	0.45	0.0006	0.60
Initial rank: Private	0.8881	0.0471	2.81	0.0016	0.66	0.0308	2.99	0.0213	3.73	0.0097	1.04
Year of enlistment
1861	0.2441	NI		NI		NI		NI		NI
1862	0.4028	−0.0072	−0.52	0.0029	1.06	−0.0357	−4.14	−0.0031	−0.54	0.0087	1.09
1863	0.0637	0.0216	0.88	−0.0022	−0.70	−0.0275	−2.12	−0.0049	−0.55	−0.0209	−1.79
1864	0.2220	−0.0914	−6.17	−0.0042	−1.27	−0.0519	−6.13	−0.0067	−1.08	−0.0248	−3.05
1865	0.0674	−0.0908	−4.39	−0.0042	−1.16	−0.0347	−2.86	0.0147	1.33	−0.0614	−8.54
County characteristics in 1850
In(wealth per capita)	4.9827	−0.0040	−0.38	0.0008	0.49	−0.0081	−1.19	−0.0033	−0.75	0.0104	1.65
In(population mortality rate)	−4.4191	−0.0555	−3.39	−0.0018	−0.63	−0.0027	−0.25	−0.0067	−1.04	−0.0094	−1.01
Population density per acre /1,000	0.3703	0.0003	0.16	−0.0535	−4.94	0.0003	0.35	0.0005	0.58	−0.0013	−1.08
LR χ²(p-value)		128.84 (0.000)		80.33 (0.000)		76.36 (0.000)		162.69 (0.000)		83.41 (0.000)
Pseudo R²		0.0157		0.0299		0.0167		0.0615		0.0223

Notes: The coefficient presents the marginal effect of probit regression. The analysis is based on 6,855 veterans who are linked to the 1850 census. Urban areas are defined by cities whose populations were over 25,000 in 1860.