In: Statistics and Probability
ou've surveyed all of the instructors in the CRMJ department at WSU asking what their current research interests are. They fall into these three categories: policing, corrections, courts. You want to know if the gender of the instructor affects their research interest. Of the women in the department, 10 are researching police, 8 are researching corrections, and 15 are researching courts. Of the men in the department, 16 are researching police, 10 are researching corrections, and 6 are researching courts. Set alpha to 0.05.
Identify the dependent and independent variables. Write out the null and alternative hypotheses. Calculate a test statistic, and interpret your results. Round all answers to 2 decimal points (0.00).
independent variables are gender of instructor
dependent variable research interest
Null : gender of instructor and research interest are independent
Alternate : gender of instructor and research interest are not independendent
This is chi-square test of independence problem
c1 | c2 | c3 | sum | |||||
r1 | 10 | 8 | 15 | 33 | ||||
r2 | 16 | 10 | 6 | 32 | ||||
sum | 26 | 18 | 21 | 65 | ||||
Eij | 1 | 2 | 3 | |||||
expected | 1 | 13.2 | 9.138462 | 10.66154 | ||||
2 | 12.8 | 8.861538 | 10.33846 | |||||
Oi | 10 | 8 | 15 | 16 | 10 | 6 | ||
Ei | 13.2 | 9.138462 | 10.66154 | 12.8 | 8.8615 | 10.338 | ||
sum | ||||||||
(Oi-Ei)^2/Ei | 0.775758 | 0.141829 | 1.765435 | 0.8 | 0.1463 | 1.8206 | 5.450 | |
alpha | 0.01 | |||||||
critical value | 9.210 | |||||||
p-value | 0.0655 |
TS = 5.450
df = (3-1)(2-1) = 2
critical value = 5.991 {=CHISQ.INV(1-0.05,2)}
since TS< critical value
we fail to reject the null hypothesis
we conclude that there is not evidence that both variable are not independent