Case Processing Summary Cases Valid Missing Total N Percent N Percent N Percent
ID: 3355945 • Letter: C
Question
Case Processing Summary
Cases
Valid
Missing
Total
N
Percent
N
Percent
N
Percent
asbestos * lungca
280
100.0%
0
0.0%
280
100.0%
asbestos * lungca Crosstabulation
lungca
Total
Yes
No
asbestos
Yes
Count
97
33
130
Expected Count
52.0
78.0
130.0
No
Count
15
135
150
Expected Count
60.0
90.0
150.0
Total
Count
112
168
280
Expected Count
112.0
168.0
280.0
Chi-Square Tests
Value
df
Asymp. Sig. (2-sided)
Exact Sig. (2-sided)
Exact Sig. (1-sided)
Pearson Chi-Square
121.154a
1
.000
Continuity Correctionb
118.476
1
.000
Likelihood Ratio
132.066
1
.000
Fisher's Exact Test
.000
.000
N of Valid Cases
280
a. 0 cells (0.0%) have expected count less than 5. The minimum expected count is 52.00.
b. Computed only for a 2x2 table
Risk Estimate
Value
95% Confidence Interval
Lower
Upper
Odds Ratio for asbestos (Yes / No)
26.455
13.622
51.376
For cohort lungca = Yes
7.462
4.569
12.185
For cohort lungca = No
.282
.209
.381
N of Valid Cases
280
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Note: Scores are to be entered by instructor
1. From the SPSS output generated in this week’s Assignment 1, copy only your odds ratio analysis (“Risk Estimate”) portion of the output and paste, below:
Answer: ____ / 10 points
Risk Estimate
Value
95% Confidence Interval
Lower
Upper
Odds Ratio for asbestos (Yes / No)
26.455
13.622
51.376
For cohort lungca = Yes
7.462
4.569
12.185
For cohort lungca = No
.282
.209
.381
N of Valid Cases
280
The p-value associated with a chi-square test only suggests whether or not the results are statistically significant. Why is it important to also look at the odds ratio?
Answer: It helps estimate the relative risk when there is a sample provided based on two probabilities. It can be calculated no matter what row or column is compared. ____ / 10 points
What does the odds ratio value in the SPSS output tell you, specifically, about lung cancer and exposure to asbestos?
Answer: ____ / 10 points
Based on your answer above, would you say there is a strong association between asbestos exposure and lung cancer?
Answer: ____ / 10 points
5. From the SPSS output generated in this week’s Assignment 1, copy only your “asbestos * lung cancer Crosstabulation” portion of the output and paste, below:
Answer: ____ / 10 points
asbestos * lungca Crosstabulation
lungca
Total
Yes
No
asbestos
Yes
Count
97
33
130
Expected Count
52.0
78.0
130.0
No
Count
15
135
150
Expected Count
60.0
90.0
150.0
Total
Count
112
168
280
Expected Count
112.0
168.0
280.0
Using the formula provided in this week’s Learning Resources, and the data in the cross-tabulation output, calculate the odds ratio and show your work in your answer, below.
Answer: ____ / 10 points
Case Processing Summary
Cases
Valid
Missing
Total
N
Percent
N
Percent
N
Percent
asbestos * lungca
280
100.0%
0
0.0%
280
100.0%
Explanation / Answer
Questions 1 & 2 have been answered. Answers to the rest of the questions are as below:
3. The odds ratio value in the SPSS output tells us that the asbestos is associated with the increased odds of lung cancer. The odds of developing lung cancer after exposure to asbestos is 26.5x that of a non exposed individual to develop lung cancer.
4. Yes, there is a strong association between asbestos exposure and lung cancer. The odds ratio value indicates that there is relative risk of 7.462 that are at risk of lung cancer with exposure to asbestos, while the relative risk for not having lung cancer with exposure to asbestos is 0.282. Therefore there is a higher risk of having lung cancer with exposure to asbestos.
5. An Odds Ratio is a measure of association between an exposure (i.e. asbestos) and an outcome (i.e. lung cancer). The Odds Ratio are used to determine whether a particular exposure is a risk factor.
Odds Ratio = (a/b) / (c/d) = (97/33) / (15/135) = 2.9394/0.1111 = 26.455