More coal is removed per hour of work, causing a drop in both mining costs and coal prices.
However, a new Energy Laboratory study suggests that those national statistics do not tell the whole story. When the researchers analyzed productivity data for more than nineteen thousand mines from 1972 through 1995, they found that some regions and some technologies lagged far behind others. Detailed analyses of why productivity changed brought some unexpected results. For example, even after accounting for geology and technology, bigger mines were more productive than smaller ones. And prices affect the national aggregates.