Michael Kinsley's Aug. 1 op-ed column, "Do the Math," examined U.S. economic performance from 1960 through 2002. He concluded that, on average, the economy performed better under Democratic presidents than under Republican presidents. But he did not consider what party had control of Congress, which is also important.

For six of 20 years with Democratic presidents, the Republicans controlled both houses of Congress. Moreover, the six years in question were President Bill Clinton's last six years in office -- a period of superb economic performance. Did the Republicans in Congress deserve no credit for this?

The Republicans controlled the presidency for 23 of the 43 years that Mr. Kinsley considered. The Democrats controlled at least one house of Congress for all of those 23 years and both houses of Congress for 15 of them. The only period with total Republican control, including the presidency, didn't start until 2003.

Do the Democrats deserve no blame for the bad results during some of the 15 years when they controlled both houses of Congress?

If one party controls the presidency and the other party controls both houses of Congress, it cannot be honestly claimed that either party is in charge. For the analysis to be meaningful, it would have to focus on years during which the party that controlled the presidency also controlled at least one house of Congress -- namely the John F. Kennedy, Lyndon Johnson and Jimmy Carter administrations; the first six years of Ronald Reagan's presidency; the first two years of Bill Clinton's presidency; and the present administration of George W. Bush.