Question

17. Four surgical procedures currently are used to install pacemakers. If the patient does not need to return for follow-up surgery, the operation is called a "clear" operation. A heart center wants to compare the proportion of clear operations for the 4 procedures, and collects the following numbers of patients from their own records: Procedure ABC D Total Clear 27 41217 96 Return 11159 1146 Total 38 56 30 18142 They will use this information to test for a difference among the proportion of clear operations using a chi-square test with a level of significance of 0.05. a) The test will involve degrees of freedom. (2 pts) b) The critical value of the test is (2 pts) c) The value of the test statistic is - (4 pts) d) Should the decision made suggest that the 4 procedures all have different proportions of clear operations? (2 pts)

Answer 1

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Ans. Given y Actual values Total clear 27 41 21 96 Return 146 Total 30 18 1(42 Ly Enpected values - 25.6901 12.3099 A I B LCD 37.859120228| 12.169 I qoriel 1 1801409 I so 5.83099) V x(chisquare). [CO-€) Ocobsewed values - Enpeted value E Ly 19563 chi-square values 10.0667856 0-139379 0.260569 / 0.0254 0.543995 0.0530 4058219 df=3. . (b) Critical value from chi-square table at x=0.05, df =3 critical value=708147 (C) The value of test statistic x = 7.86689 (d) A P-value =0.04884 yes the decision made suggest that the 4 procedure all have different proportion of clear operation &