Question

The use of cellular phones in automobiles has increased dramatically in the last few years. Of concern to traffic experts, as well as manufacturers of cellular phones, is the effect on accident rates. Is someone who is using a cellular phone more likely to be involved in a traffic accident? What is your conclusion from the following sample information? Use the 0.05 significance level. Had Accident in the Last Year Did Not Have an Accident in the Last Year Uses a cell phone 17 445 Does not use a cell phone 21 278 Click here for the Excel Data File H0: There is no relationship between phone use and accidents. H1: There is a relationship between phone use and accidents. State the decision rule using 0.05 significance level. (Round your answer to 3 decimal places.) Compute the value of chi-square. (Round your answer to 3 decimal places.) What is your decision regarding H0?

Answer 1

Ans:

df=(2-1)*(2-1)=1

critical chi square value=CHIINV(0.05,1)=3.841

Reject H₀,if chi square >3.841

	Observed freq.(fo)
	Had accident	dis not have	Total
use a phone	17	445	462
dis not use	21	278	299
Total	38	723	761
	Expected freq.(fe)
	Had accident	dis not have	Total
use a phone	23.070	438.930	462
dis not use	14.930	284.070	299
Total	38	723	761
	Chi squar=(fo-fe)^2/fe
	Had accident	dis not have	Total
use a phone	1.597	0.084	1.681
dis not use	2.467	0.130	2.597
Total	4.064	0.214	4.278

Test statistic:

Chi square=4.278

As,chi square>3.841,Reject the null hypothesis.