The biological factors underlying the differences in genome dynamics observed across species are likely to be complex and remains to be explored. (sciencedaily.com)
It would not reflect the causal effect of added funds on student outcomes, but rather the effects of unknown underlying differences between the districts. (educationnext.org)
The relatively high average earnings of no - pension couples in 1989 - 1991 are a factor underlying this difference. (statcan.gc.ca)