The cited data is from a paper The Validity and Utility of Selection Methods in Personnel Psychology https://www.researchgate.net/publication/232564809_The_Valid... in 1998 as a meta-analysis of other findings, but they are not specific to software development (one account is sourced from 32000 employees in 515 diverse civilian jobs in the 1980s). Maybe software is like any other job (sales, clerical, accounting) but maybe not.