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. Author manuscript; available in PMC: 2012 Dec 1.
Published in final edited form as: Int J Obes (Lond). 2011 Jul 5;36(6):866–875. doi: 10.1038/ijo.2011.134

Table 3.

Random-effects linear regression models of the adjusted association between education and BMI over survey period

Females Males
β (95% Confidence Interval) β (95% Confidence Interval)

<Primary School Referent Referent
Primary School −0.08 (−0.30, 0.15) −0.22 (−0.45, 0.00)
Secondary School −0.45 (−0.76, −0.14) 0.08 (−0.20, 0.36)
>Secondary School −0.36 (−0.74, 0.02) −0.07 (−0.46, 0.32)
Time × Primary School 0.02 (0.01, 0.04) 0.04 (0.02, 0.06)
Time × Secondary School 0.03 (0.00, 0.05) 0.04 (0.01, 0.06)
Time × >Secondary School −0.03 (−0.06, −0.01) 0.07 (0.04, 0.10)
Time 0.11 (0.10, 0.12) 0.14 (0.11, 0.18)
Mean* Time −0.09 (−0.11, −0.07) -
Time Squared - 0.00 (0.00, 0.00)
Birth Cohort (1= before 1955) −2.98 (−4.19, −1.77) 0.35 (0.06, 0.65)
Birth Cohort × Time - −0.04 (−0.06, −0.02)
Birth Cohort × Primary School −0.11 (−0.41, 0.18) -
Birth Cohort × Secondary School 0.42 (−0.32, 1.16) -
Birth Cohort × >Secondary School 0.27 (−0.27, 0.82) -
Urbanicity1 0.01 (0.01, 0.02) 0.01 (0.00, 0.02)
Mean Urbancity1,2 −0.01 (−0.02, −0.01) 0.00 (−0.01, 0.01)
Birth Cohort × Urbanicity1 −0.01 (−0.02, 0.00) −0.02 (−0.03, 0.00)
Birth Cohort × Mean Urbanicity1,2 0.04 (0.03, 0.06) 0.04 (0.03, 0.06)
Person-specific Mean Age1,2 0.20 (0.10, 0.30) 0.38 (0.33, 0.43)
Person-specific Mean Age Squared1,2 0.00 (0.00, 0.00) 0.00 (−0.01, 0.00)
Birth Cohort × Mean Age1,2 0.38 (−0.09, 0.84) -
Birth Cohort × Mean Age Squared1,2 −0.01 (−0.01, 0.00) -
Current Smoker - −0.29 (−0.39, −0.20)
Intercept 22.47 (22.17, 22.78) 21.13 (20.86, 21.41)

Number of Observations 23,068 18,693
N 7,314 6,492
1

Variable means are the person-specific/group mean value for these variables over the survey period. The coefficient on the variable for the person-specific mean represents the difference between the between and within effects for each variable. These are included for time-varying variables for which the between and within coefficients were significantly different.

2

Urbanicity, mean urbanicity, mean age and mean age squared were mean centered before inclusion in the regression.