Grier uses pooled data for the years 1961 -1990 for all of the major British, French, and
Spanish ex-colonies. As in Grier (1995), he converted the 30 years of annual data into six
5 year averaged observations per country. He then uses five year averages because
averaging over the entire sample could result in a loss of temporal information, where the
results would be driven solely by cross-country variations.