# The data for this example come from a 1966 paper by Cyril Burt entitled "The
# genetic determination of differences in intelligence: A study of monozygotic
# twins reared apart". The data consist of IQ scores for identical twins, one
# raised by foster parents, the other by the natural parents. We also know the
# social class of natural parents (high, middle or low). Try to predict the IQ
# of the twin with foster parents from the IQ of the twin with the natural
# parents and the social class of natural parents. Cyril Burt invented some of
# his data on identical twins. In light of this, can you see anything that might
# lead one to suspect this data?

"Foster" "Biological" "Social"
"1" 82 82 "high"
"2" 80 90 "high"
"3" 88 91 "high"
"4" 108 115 "high"
"5" 116 115 "high"
"6" 117 129 "high"
"7" 132 131 "high"
"8" 71 78 "middle"
"9" 75 79 "middle"
"10" 93 82 "middle"
"11" 95 97 "middle"
"12" 88 100 "middle"
"13" 111 107 "middle"
"14" 63 68 "low"
"15" 77 73 "low"
"16" 86 81 "low"
"17" 83 85 "low"
"18" 93 87 "low"
"19" 97 87 "low"
"20" 87 93 "low"
"21" 94 94 "low"
"22" 96 95 "low"
"23" 112 97 "low"
"24" 113 97 "low"
"25" 106 103 "low"
"26" 107 106 "low"
"27" 98 111 "low"