The null and alternative hypotheses A. H₀ Injuries and helmet color are independent Hy: Injuries and helmet color are dependent
What are the hypotheses?
The null and alternative hypotheses for the chi-square test of independence are typically :
Null : There is no association between the two variables (they are independent ).
Alternate : There is an association between the two variables (they are not independent).
Based on the choices given in the question (A to D), the correct hypotheses to be tested would be:
Null : Injuries and helmet color are independent.
Alternate : Injuries and helmet color are dependent.
The full question is:
A case-control (or retrospective) study was conducted to investigate a relationship between the colors of helmets worn by motorcycle drivers and whether they are injured or killed in a crash. Results are given in the accompanying table. Using a 0.01 significance level, test the claim that injuries are independent of helmet color,
Color of Helmet
Black White Yellow Red Blue
Controls (not injured) 482 341 30 168 94
Cases 203 110 9 69 44
(injured or killed)
Identify the null and alternative hypotheses. Choose the correct answer below O A. H₀ Injuries and helmet color are independent Hy: Injuries and helmet color are dependent
B. H₀ Injuries and helmet color are dependent Hy Injuries and helmet color are independent
C. H₀ Whether a crash occurs and helmet color are independent H, Whether a crash occurs and helmet color are dependent
D. H₀ Whether a crash occurs and helmet color are dependent H: Whether a crash occurs and helmet color are independent