Presentation

7.29 Murders and poverty, Part I.

The following regression output is for predicting annual murders per million 
from percentage living in poverty in a random sample of 20 metropolitan areas.

(a) Write out the linear model.
    Annual_murders = -29.901 + 2.559 * % in poverty 

(b) Interpret the intercept.
    When % in poverty = 0 ie no poverty, expected murder rate in metropolitan
    areas is -29.901 per million. This is obviously not a meaningful value, it 
    just serves to adjust the height of the regression line.

(c) Interpret the slope
    For each additional percentage increase in poverty, we expect murders per 
    million to be higher on average by 2.559.

(d) Interpret R^2
    Poverty level explains 70.52% of the variability in murder rates
    in metropolitan areas.

(e) Calculate the correlation coefficient.

(R <- sqrt(0.7052))

## [1] 0.8397619