Need help with filling the blanks on this one. Part of it has already been answered. I need help filling in where there are "??" question marks. CMV infection and coronary restenosis. Exercise 18.3 found that 43% of CMV+ experienced arterial restenosis within 6 months of atherectomy. In contrast, 8% of CMV- patients experienced a similar outcome. Table 18.8 contains observed counts.

1. Repeat the test with a z-statistic. Show the relation between the chi-square statistic and the z-statistic.

[Even though the book asks for the z test, the sample size requirements are not met for the z test. Just proceed anyway, noting the issue] Hypotheses:

H0: ??

Ha: ??

Assumptions ?????

We use Stata to compute our test statistic and P-value: . prtesti 49 0.42857 26 0.07692, level(95)

Two-sample test of proportions x: Number of obs = 49

y: Number of obs = 26

------------------------------------------------------------------------------

| Mean Std. Err. z P>|z| [95% Conf. Interval]

-------------+----------------------------------------------------------------

x | .42857 .0706959 .2900085 .5671315

y | .07692 .052258 -.0255038 .1793438

-------------+----------------------------------------------------------------

diff | .35165 .0879137 .1793424 .5239576

| under Ho: .1118792 3.14 0.002

------------------------------------------------------------------------------

diff = prop(x) - prop(y) z = 3.1431

Ho: diff = 0

Ha: diff < 0 Ha: diff != 0 Ha: diff > 0

Pr(Z < z) = 0.9992 Pr(|Z| > |z|) = 0.0017 Pr(Z > z) = 0.0008

Results: ???

Interpretation: ??????

Conclusion: ????

Relationship between z stat and chisquare stat: ????