23Although these results suggest that the earnings of recent immigrants approach those of natives, they do not imply that the earnings of recent immigrants, will on aver-age, exceed those of natives. According to the IHIC model, the incentive for human capital investment decreases with age and as source-country human capital becomes more transferable; it suggests that the strength of the inverse relationship between initial earnings and earnings growth decreases with immigrant time in the United States. This theoretical expectation is supported in research following immigrants for 20 years. Duleep and Regets (2002) found that although the inverse relationship continues beyond the initial 10-year period (the earnings growth increase associ-ated with lower initial earnings continues beyond the initial 10-year period), it is about one-third of the 10-year effect. The decrease in the ratio of immigrant-to-native earn-ings growth rates is also apparent in the longitudinal data discussed in the section “Evidence from Longitudinal Data” below.24 This strong inverse relationship between relative entry earnings for an immigrant cohort and its subsequent rela-tive earnings growth rate has been explored theoretically and empirically in a number of recent papers (Duleep and Regets 1992, 1994a, 1994b, 1996a, 1996b, 1996c, 1997a, 1997b, 1999, 2002).