2. A randomized experiment was conducted in which patients with coronary artery

Question

2. A randomized experiment was conducted in which patients with coronary artery disease either had angioplasty or bypass surgery. The table shows the observed incidence of angina (chest pain) among the patients five years after the treatment. Treatment Angina Angioplasty Bypass Total Yes 111 (E: ) 74 (E: 185 No 402 (E 441 (E: 843 Total 513 515 1028 Perform a nondirectional chi-square hypothesis test for 2x2 contingency tables to determine whether there is any association between treatment type and incidence of angina. Let = 0.01 Formulas for #2 column total × row total x: =(0-E)-, E- df = 1. Grand total

Explanation / Answer

H0: There is no relation between treatment type and incidence of angina

Ha: There is a  relation between treatment type and incidence of angina

alpha:1%

Test statistic:

chi square=9.2

chi square critical value at 1 df with 1% level=6.63

Conclusion: chi square cal > chi square crirical value, we reject the Ho. Hence claim is signiificant

Oi ei (oi-ei)^2/ei 111 92.3200389 3.77968803 74 92.6799611 3.76500963 402 420.679961 0.8294689 441 422.320039 0.82624767 sum= 9.20041424

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