Question 3: Now make cough the row variable and history of bronchitis the column variable. (This was how the table was presented in the lecture.) Carry out the chi-squared test of association and calculate the odds ratio and the relative risk. How do the results change?
We choose Analyze, Descriptive Statistics, Crosstabs. Put the variable 'Bronchitis by age 5' into Row(s): and 'Day or night cough at age 12' into Column(s):. Click Statistics, Chisquare, Continue. Click OK.
You should get the case processing summary and then the following:
Day or night cough at age 12 * Bronchitis by age 5 Crosstabulation | ||||
---|---|---|---|---|
Count | ||||
Bronchitis by age 5 | Total | |||
Yes | No | |||
Day or night cough at age 12 | Yes | 26 | 44 | 70 |
No | 247 | 1002 | 1249 | |
Total | 273 | 1046 | 1319 |
Chi-Square Tests | |||||
---|---|---|---|---|---|
Value | df | Asymp. Sig. (2-sided) | Exact Sig. (2-sided) | Exact Sig. (1-sided) | |
Pearson Chi-Square | 12.180^{a} | 1 | .000 | ||
Continuity Correction^{b} | 11.145^{ } | 1 | .001 | ||
Likelihood Ratio | 10.609^{ } | 1 | .001 | ||
Fisher's Exact Test | .001 | .001 | |||
Linear-by-Linear Association | 12.171^{ } | 1 | .000 | ||
N of Valid Cases | 1319^{ } | ||||
^{a} 0 cells (.0%) have expected count less than 5. The minimum expected count is 14.49 | |||||
^{b} Computed only for a 2x2 table |
Risk Estimate | |||
---|---|---|---|
Value | 95% Confidence Interval | ||
Lower | Upper | ||
Odds Ratio for Day or night cough at age 12 (Yes / No) | 2.397 | 1.448 | 3.970 |
For cohort Bronchitis by age 5 = Yes | 1.878 | 1.358 | 2.598 |
For cohort Bronchitis by age 5 = No | .784 | .653 | .940 |
N of Valid Cases | 1319 |
There are the following differences:
Back to Exercise: Cough during the day or at night and history of bronchitis.
To Applied Biostatistics index.
To Martin Bland's M.Sc. index.
This page maintained by Martin Bland.
Last updated: 20 February, 2012.