In: Statistics and Probability
Lung Cancer |
No Lung Cancer |
Total |
|
Asbestos Exposure |
153 |
201 |
354 |
No Asbestos Exposure |
23 |
664 |
687 |
Total |
176 |
865 |
1041 |
(a)
Given that,
possible chances (x)=176
sample size(n)=1041
success rate ( p )= x/n = 0.1691
success probability,( po )=0.18
failure probability,( qo) = 0.82
null, Ho:p=0.18
alternate, H1: p!=0.18
level of significance, alpha = 0.05
from standard normal table, two tailed z alpha/2 =1.96
since our test is two-tailed
reject Ho, if zo < -1.96 OR if zo > 1.96
we use test statistic z proportion = p-po/sqrt(poqo/n)
zo=0.16907-0.18/(sqrt(0.1476)/1041)
zo =-0.9181
| zo | =0.9181
critical value
the value of |z alpha| at los 0.05% is 1.96
we got |zo| =0.918 & | z alpha | =1.96
make decision
hence value of |zo | < | z alpha | and here we do not reject
Ho
p-value: two tailed ( double the one tail ) - Ha : ( p != -0.91807
) = 0.35858
hence value of p0.05 < 0.3586,here we do not reject Ho
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null, Ho:p=0.18
alternate, H1: p!=0.18
test statistic: -0.9181
critical value: -1.96 , 1.96
decision: do not reject Ho
p-value: 0.35858
no evidence that proportion of lung cancer patients is different
than the national average of 18%
(b)
CI = confidence interval
confidence interval = [ 0.1691 ± 1.96 * Sqrt ( (0.1691*0.8309)
/1041) ) ]
= [0.1691 - 1.96 * Sqrt ( (0.1691*0.8309) /1041) , 0.1691 + 1.96 *
Sqrt ( (0.1691*0.8309) /1041) ]
= [0.1463 , 0.1918]
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interpretations:
1. We are 95% sure that the interval [ 0.1463 , 0.1918] contains
the true population proportion
2. If a large number of samples are collected, and a confidence
interval is created
for each sample, 95% of these intervals will contains the true
population proportion