A preliminary investigation focussed on single scales created from summing all 12 on SMFQ items (possible total score zero to 24). Here there was strong evidence of a sex difference (p < .001) across all four time points with females scoring consistently higher than males. The difference was most marked at the third time point (16 years 6 months). Estimated sex difference at 12 years 10 months = 0.56 points [0.41, 0.72]; difference at 13 years 10 months = 1.11 [0.93, 1.29]; difference at 16 years 6 months = 1.75 [1.50, 1.99], difference at 17 years 10 months = 0.96 [0.71, 1.21]. Estimated mean SMFQ scores were minimally affected when restricting the sample to those with complete symptom data and this sample restriction also had little impact on the sex differences observed.
