Gaps in educational achievement and shifts in technology, often cited as key reasons for widening income and wealth inequality, do very little to explain the trend, said Lawrence Mishel, president of the Economic Policy Institute, a liberal think tank in Washington.

Speaking Saturday at a conference on “Equality of Economic Opportunity” hosted by the Federal Reserve Bank of Boston, Mr. Mishel criticized the event’s narrow focus on local actions to reduce inequality when other possible approaches lie in the realm of broader economic policy.