The average value of RM-RF (the average premium per unit of market β) is 0.43% per month. This is large from an investment perspective (about 5% per year), but it is a marginal 1.76 standard errors from 0.The average SMB return (the average premium for the size-related factor in returns) is only 0.27% per month (t = 1.73). We shall find, however, that the slopes on SMB for the 25 stock portfolios cover a range in excess of 1.7, so the estimated spread in expected returns due to the size factor is large, about 0.46% per month. The book-to-market factor HML,produces an average premium of 0.40% per month (t = 2.91), that is large in both practical and statistical terms.