# Exercise: Cough during the day or at night and history of bronchitis

Parents of children in the Kent Respiratory Study completed questionnaires when their children were aged five and twelve (Bland et al., 1974).

The data used in the lecture are available as an SPSS file: bronch.sav.

Reference
Bland JM, Holland WW, Elliott A. (1974) The development of respiratory symptoms in a cohort of Kent schoolchildren. Bulletin Physio-Pathologie Respiratoire 10, 699-716.

## Questions

Question 1: Using SPSS, cross-tabulate cough by history of bronchitis, making history of bronchitis the row variable and cough the column variable. Carry out a chi-squared test of association.

Question 2: Calculate the odds ratio for the relationship and the relative risk of cough for children with bronchitis before age five compared to those without bronchitis before age five. Quote the results to two decimal places.

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?

Question 5: Why does SPSS put the words 'For cohort' in the Risk Estimate table?