25
terminal statures, 171.72 and 171.99 cms respectively. If, on the other hand, soldier and
prisoner statures are observed at US insolation extremes, the soldier-prisoner stature
differential was large. For example, observed at the lowest state-insolation level, Maine,
soldiers were shorter than prisoners, 171.04 to 171.81 centimeters, respectively.
Observed at the highest state-insolation level, Arizona, prisoners were taller than soldiers,
167.15 to 158.7 centimeters, respectively. The prisoner stature advantage in insolation
indicates prisoner’s, who likely received smaller stature benefits from other sources and
had larger stature growth with insolation. Therefore, there was an absolute maximum
stature that whites reach with insolation, and insolation effects differed by socioeconomic
9
status at the extremes.
Sensitivity analysis indicates the omission of insolation had considerable
interaction with nativity. A joint test for soldiers and prisoner statures on insolation
variables illustrates that insolation’s omission over estimates the effect of nativity with
stature, while having little effect on other variable slope coefficients; insolation omission
also upwardly biases the intercept (Soldiers, F-Statistic: 48.36, p=.0000; Prisoners, F-
Statistic: 14.68, p=.0000), indicating that when insolation is omitted the asymptotic bias
on stature with nativity variables and the intercept are positive (Woolridge, 2002, p. 62;
Woolridge, 2003. p. 92, Table 3.2).
Third, after controlling for insolation, 19th century farmers were at a biological
advantage to workers in other occupations, and the farmer stature advantage for both
soldiers and prisoners was remarkably similar (Table 3, Models 1 and 4). Farmers
9 Average US insolation is 4.33; average Maine insolation is 3.43; average Missouri insolation is 4.16;
average Arizona is 5.22.