A Sociology student investigated the association between a country’s Literacy Rate and Life Expec- tancy, and then drew the conc
lusions listed below. Explain why each statement is incorrect. (Assume that all the calculations were done properly.) a) The determines 64% of the Life Expectancy for a country.
b) The slope of the line shows that an increase of 5% in will produce a 2-year improvement in
(a) R2 does not determine the level of correlation between two variables in statistics but rather it is used to determine the level of variance in a dependent variable that is explained by an independent variable. It is also known as coefficient of determination.
Pearson's correlation coefficient (r) will better explain a direct relationship between a country's literacy rate and life expectancy and the value obtained will better explain option a
(b) The slope of the line can predict an improvement in life expectancy but cannot guarantee this improvement. And as such, the use of the word "will" suggests a form of guarantee which is wrong in interpreting slopes.
