# Suggested answers to exercise: Cough during the day or at night and history of bronchitis, 4

Question 4: When cough is the row variable and history of bronchitis the column variable, how can we interpret the Risk Estimate table?

This is the Risk Estimate table output by SPSS:

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

We have odd ratio = 2.40 with 95% confidence interval = 1.45 to 3.97, as before.

The second row of the table gives the relative risk of having a history of bronchitis for those children reported to cough, compared to the risk of having a history of bronchitis for those children not reported to cough. It was found by (26/70) / (247/1249) = 1.878.

The third row of the table gives the relative risk of not having a history of bronchitis for those children reported to cough, compared to the risk of not having a history of bronchitis for those children not reported to cough. It was found by (44/70) / (1002/1249) = 0.784.

Neither of these relative risks is much use.