A case-control (or retrospective) study was conducted to investigate a relations

Question

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 White Yellow Black 473 151 64 102 50 (not injured) 339 Cases (injured or killed) 210 H: Injuries and helmet color are dependent Ho: Whether a crash occurs and helmet color are independent H: Whether a crash occurs and helmet color are dependent D. Compute the test statistic. (Round to three decimal places as needed.) Enter your answer in the answer box and then click Check Answer Clear All Check Answer

Explanation / Answer

Ho:

injuries and helmet colour are indpendent.

Ha:

injuries and helmet colour are dependent.

alpha=0.01

Chi sq test for independence

Calculate expected frequencies

E=Row total*colum tot/grand tot.

given frequencies are observed values O

Chi sq statistic as

Chi sq=(O-E)^2/E

ANSWER:12.465

0 E O-E (O-E)^2 (0-E)^2/E 473 490.4855 -17.4855 305.7443 0.62335 339 313.8246 25.17543 633.8021 2.019606 28 25.13469 2.865309 8.209995 0.32664 151 154.3988 -3.39882 11.55196 0.074819 102 109.1564 -7.15637 51.21368 0.469177 210 192.5145 17.48555 305.7443 1.588163 98 123.1754 -25.1754 633.8021 5.145524 7 9.865309 -2.86531 8.209995 0.832209 64 60.60118 3.398817 11.55196 0.190623 50 42.84363 7.156373 51.21368 1.195363 CHI SQ STAT 12.46547

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.