# Statistics - Regression Analysis

13.30 A researcher used stepwise regression to create regression models to predict BirthRate (births per

1,000) using five predictors: LifeExp (life expectancy in years), InfMort (infant mortality rate),

Density (population density per square kilometer), GDPCap (Gross Domestic Product per capita),

and Literate (literacy percent). Interpret these results.

Regression Analysis-Stepwise Selection (best model of each size)

153 observations

BirthRate is the dependent variable

p-values for the coefficients

Nvar LifeExp InfMort Density GDPCap Literate s Adj R2 R2

1 .0000 6.318 .722 .724

2 .0000 .0000 5.334 .802 .805

3 .0000 .0242 .0000 5.261 .807 .811

4 .5764 .0000 .0311 .0000 5.273 .806 .812

5 .5937 .0000 .6289 .0440 .0000 5.287 .805 .812

13.32 An expert witness in a case of alleged racial discrimination in a state university school of nursing

introduced a regression of the determinants of Salary of each professor for each year during an

8-year period (n = 423) with the following results, with dependent variable Year (year in which

the salary was observed) and predictors YearHire (year when the individual was hired), Race (1 if

individual is black, 0 otherwise), and Rank (1 if individual is an assistant professor, 0 otherwise).

Interpret these results.

Variable Coefficient t p

Intercept −3,816,521 −29.4 .000

Year 1,948 29.8 .000

YearHire −826 −5.5 .000

Race −2,093 −4.3 .000

Rank −6,438 −22.3 .000

R2 = 0.811 R2

adj = 0.809 s = 3,318

https://brainmass.com/statistics/regression-analysis/statistics-regression-analysis-242236

#### Solution Summary

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