7.41 Murders and poverty, Part II. Exercise 7.29 presents regression output from a model for predicting annual murders per million from percentage living in poverty based on a random sample of 20 metropolitan areas. The model output is also provided below. | Estimate | Std. Error | t value | Pr(>|t|) | | (Intercept) | -29.901 | 7.789 | -3.839 | 0.001 | | poverty% | 2.559 | 0.390 | 6.562 | 0.000 | | s =5.512 | R2 = 70.52% | R2adj = 68 .89% |
(a)What are the hypotheses for evaluating whether poverty percentage is a significant predictor of murder rate? H0 = Poverty% is not a significant predictor of murder rates Ha = Poverty% is a significnat predictor of murder rates
State the conclusion of the hypothesis test from part (a) in context of the data. p-value of poverty% is approximately 0 which leads us to reject the null hypothesis and conclude that there is sufficient evididence that poverty% is a significant predictor of murder rates.
Calculate a 95% confidence interval for the slope of poverty percentage, and interpret it in context of the data. For each % increase in poverty we expect the murder rate, on average, to increase by 1.73964 to 3.37836.
n = 20
df = n-2
tv = 1-(0.05/2)
t <- qt(tv, df)
t
## [1] 2.100922
est = 2.559
se = 0.390
ci_low <- est-t*se
ci_upp <- est+t*se
ci_low
## [1] 1.73964
ci_upp
## [1] 3.37836