 Much of McKenzie's research on microenterprises has been conducted with Suresh de Mel and Woodruff in Sri Lanka.In one study, after randomly assigning cash grants to microentrepreneurs, they find annual real returns to capital of 55-63% per year, i.e., much higher than prevailing market interest rates, with the returns varying by entrepreneurial ability and household wealth, but not by risk aversion, suggesting that insufficient access to credit might not be a key constraint.Faced with the difficulty of measuring profits, they find that simply asking firms about their profits offers a more accurate measure than detailed questions on revenues and expenses, as firms tend to underreport a nearly a third of their revenues, and that while providing entrepreneurs with account diaries helps address that issue, it doesn't significantly change reported profits.