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Table 1 Example of calculation: Estimated effect of time trend in reported intake of pasta 1986–99 on mean hip-circumference in men:

From: Reported food intake and distribution of body fat: a repeated cross-sectional study

   (ii) Δlevel1–8   
Reported intake frequency level Proportion 19991 Proportion 19861 (i) partial regression coefficientsβlevel1–8 2 (iii) Estimated effect on mean HC: Σ(Δi * βi) i = level 1–8
Never 1 (3/631 - 7/777)* -5.7 = 0.024 mm
1/year 2 (19/631 - 59/777)* -5.4 = 0.247 mm
1–3/month 3 127/631 408/777 reference category 3
1/week 4 (243/631 - 262/777)* -0.2 = -0.010 mm
2–3/week 5 (199/631 - 40/777)* 4.3 = 1.135 mm
4–5/week 6 (31/631 - 1/777)* 7.8 = 0.373 mm
1/day 7 (8/631 - 0/777)* 10.6 = 0.134 mm
2–3/day 8 (1/631 - 0/777)* 13.4 = 0.021 mm
total      1,925 mm
  1. 1number of valid answers reporting specific number of intakes divided by total number of valid answers in respective survey-year.
  2. 2intake-level specific partial β-coefficients for association with hip-circumference estimated from all valid answers '86+'90+'94+'99.
  3. 3Level 3 is the reference category and therefore not included in the calculation.