In the chapter we saw a study by Trzesniewski et al. (2008) on trends in narcissism scores over time. They also reported data on self-enhancement, which is the tendency to hold unrealistically positive views of oneself. The measure of self-enhancement (SelfEn) was obtained by asking students to respond on a 1–10 scale rating their intelligence relative to others. The researchers then calculated the difference between the rating predicted from SAT scores and the rating the student gave. The data are presented below. Positive scores represent self-enhancement.

Year 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 SelfEn .06 .03 .00 .01 .07 .06 .04 .03 .03 .03 .03 .07 .06 .03 .03 Year 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 SelfEn .04 .01 2.01 2.02 .02 .05 .00 .01 2.01 2.02 2.06 2.08 2.10 2.11 2.08 2.08

(a) From these data can we say something about what changes have taken place in selfenhancement scores of college students over the years?

(b) With several hundred thousand students in the combined sample, the authors of the original study actually based their analyses on individual scores rather than yearly means to make the same computation. They found a correlation of .03, which differs considerably from your result. Why is this not surprising?

(c) Which is the correct correlation for this question (yours or the authors’), or are they both correct?