9.1 Suppose you just read a careful statistical study of the effect of improved health of children on their test scores at school. Using data from a project in a West African district, in 2000, the study concluded that students who received multivitamin supplements performed substantially better at school. Use the concept of external validity to determine if these results are likely to apply to India in 2000, the United Kingdom in 2000, and West Africa in 2015.