SOME COUNTRIES PRODUCE SO MUCH MORE OUTPUT PER WORKER THAN OTHERS: Robustness of the Results 2

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The fourth specification examines the ethnolinguistic fractionalization (ELF) index computed by Taylor and Hudson (1972) and used by Mauro (1995). ELF measures the probability that any two people chosen at random from within a country will belong to different ethnic or linguistic groups. While the simple association of this variable with output per worker is quite strong, the partial regression coefficient is small in magnitude (the variable is measured on a [0,1] scale) and statistically insignificant.

The fifth specification adds religious affiliation variables to the specification. Specifically, these variables measure the fraction (on a [0,1] scale) of a country’s population affiliated with the Catholic, Muslim, Protestant, and Hindu religions. The point estimate on social infrastructure is changed little when these variables are included in the specification. Both Catholic and Muslim affiliation variables enter significantly into the regression, while the Protestant and Hindu variables do not.

The sixth specification adds the log of population to the regression. A number of recent growth models in the tradition of Romer (1990) emphasize that nonrivalry of ideas should lead to increasing returns to scale. Our simple attempt to measure scale with population does not find evidence of this effect. One explanation is that national boundaries do not limit the areas where ideas are applied.