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. 1999 Jul 20;96(15):8790–8794. doi: 10.1073/pnas.96.15.8790

Table 2.

IQ gains for mildly retarded and upper borderline adopted children

Mean IQ
IQ gains
Before adoption After adoption
MR (n = 10) 65.7  (3.7) 80.2  (11.9) 14.5  (12.7)
UB (n = 27) 83.0  (1.6) 95.1  (15.4) 12.1  (15.2)

To test the significant difference between before-after adoption IQs, t test for dependence samples were used. For MR: t = 3.6, P = 0.006; for UB: t = 4.12, P = 0.0003. The Spearman R correlation between IQs before adoption and adoptive SES is 0.08, P = 0.64; therefore, there is no selective placement between these IQs and adoptive SES. MR, mildly retarded; UB, upper borderline.