Church attendance was measured by the response to the item ‘When you were between the ages of x and y, how often would you attend religious services ?’ asked in our MM3 interview for ages 12–14 and 15–17. Response options were ‘more than once a week’, ‘once a week’, ‘a few times a month’, ‘once a month’, ‘less than once a month’ and ‘never’. Test–retest reliability, as assessed by the intraclass correlation coefficient (ICC), of this variable for these two time periods was +0.77 and +0.83 respectively.
