Recent evidence has surfaced regarding the effect of multiple CAT scans on the increase in risk...

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Recent evidence has surfaced regarding the effect of multipleCAT scans on the increase in risk for blood related cancers inchildren aged 5-18. Suppose after selecting 267 cases of childhoodcancers, researchers found that 139 had received one or more CATscans. Of the 382 matched sibling controls without blood cancers,only 89 reported having exposure to one or more CAT scan.

A) Calculate the risk difference between the groups fordeveloping blood cancer based on exposure to one or more CAT scansversus never having received a CAT scan.

B) Construct a confidence interval about your point estimate forthe difference in risk.

C) Carry out a formal statistical test to determine if there isa significant difference in risk between the groups.

Choose the most appropriate option

option 1   

A) risk difference=0.881

B) CI=(0.12, 0.63)

C) ) Ho: p1=p2; Ha: p1≠p2

Z stat=9.7

Pvalue: <0.0001

Option2             

A) risk difference=0.288

B) CI=(0.21, 0.36)

C) ) Ho: p1=p2; Ha: p1≠p2

Z stat=7.7

Pvalue: <0.0001

Option 3   

A) risk difference=0.128

B) CI=(0.06, 0.16)

C) ) Ho: p1=p2; Ha: p1≠p2

Z stat=5.6

Pvalue: <0.01

Answer & Explanation Solved by verified expert
3.7 Ratings (648 Votes)

A B
x1                =    139 x2                =    89
p̂1=x1/n1 = 0.5206 p̂2=x2/n2 = 0.2330
n1                       = 267 n2                       = 382
estimated difference in proportion   =p̂1-p̂2   = 0.2876

B)

for 95 % CI value of z= 1.960
margin of error E=z*std error = 0.0734
lower bound=(p̂1-p̂2)-E= 0.2142
Upper bound=(p̂1-p̂2)+E= 0.3610
from above 95% confidence interval for difference in population proportion =(0.21,0.36)

C(

std error Se=√(p̂1*(1-p̂1)*(1/n1+1/n2) = 0.0381
test stat z=(p̂1-p̂2)/Se = 7.70

Pvalue: <0.0001

option 2 is corect

A) risk difference=0.288

B) CI=(0.21, 0.36)

C) ) Ho: p1=p2; Ha: p1≠p2

Z stat=7.7

Pvalue: <0.0001


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