Question

Do poorer people tend to have shorter lives than richer people? Two researchers ranked all counties in the United States by their poverty level and then divided them into 20 groups, each representing approximately 5% of the overall U.S. population. The bottom 5% were the least impoverished (wealthiest) and top 5% (the 100th percentile) the most impoverished. Life expectancies at birth for each of the 20 groups were calculated based on life tables. Here are the data poverty percentiles (higher percentiles correspond to greater poverty) and life expectancies at birth (in years) in 2010 for males in the 20 groups

Percentile rank 5 10 15 20 25 30 35 40 45 50

Life expectancy of males 79 79 78 77.5 77.5 77.5 77 76.5 77 77

Percentile rank 55 60 65 70 75 80 85 90 95 100

Life expectancy of males 76.5 76 76 77 76.5 75 75.5 74 74 73

a. Make a scatterplot that shows how life expectancy responds to changes in poverty level percentile rank.

b. Describe the overall pattern of the data. Find the correlation r between life expectancy and poverty level percentile rank.

Answer 1