Net income includes purchased research and development expenses of $594 million in1998 and $508 million in 1997, as well as realized gains on the sale of a minority stock investment of $5 million in 1998 and $153 million in 1997. On a pro forma basis, return on average equity, excluding these nonrecurring items net of tax, would have been 40.6%, 37.2% and 30.4% for 1996, 1997 and 1998, respectively.