Chapter 8 Supplemental Tables

Table 8.1: Continuous Variable Descriptives
Variable Mean SD Median N Missing N
BMI at Age 13 - Girls 20.67 3.55 20 3199 1161
BMI Z-score at age 13 - Girls 0.26 1.08 0.23 3199 1161
Thin-Ideal Internalization at age 14 - Girls 2.02 0.5 2 3355 1005
Body Dissatisfaction at age 14 - Girls 2.77 0.97 2.64 3371 989
BMI at Age 13 - Boys 19.89 3.31 19.2 2730 589
BMI Z-score at age 13 - Boys 0.21 1.14 0.18 2730 589
Thin-Ideal Internalization at age 14 - Boys 2.08 0.57 2 2515 804
Body Dissatisfaction at age 14 - Boys 2.49 1.11 2.18 2647 672
Table 8.2: Parent Highest Occupational Class - Responses Frequencies
Response Girls N Girls % Boys N Boys %
Unskilled 0 29 0.67 28 0.84
Partially Skilled 1 179 4.11 98 2.95
Skilled Manual 2 460 10.55 333 10.03
Skilled Non-Manual 3 1058 24.27 845 25.46
Manegerial and Technical 4 1483 34.01 1220 36.76
Professional 5 368 8.44 356 10.73
Missing NA 783 17.96 439 13.23
Table 8.3: Fear of Weight Gain at Age 14 - Responses Frequencies
Response Girls N Girls % Boys N Boys %
Not at All 0 1797 41.22 2173 65.47
A Little 1 1148 26.33 371 11.18
A Lot 2 280 6.42 48 1.45
All the Time 3 118 2.71 19 0.57
Missing NA 1017 23.33 708 21.33
Table 8.4: Raw Number of Exercise State Transitions Amongst Girls
From To N
no EWL no EWL 2098
EWL no EWL 617
Maladaptive Ex no EWL 182
no EWL EWL 1003
EWL EWL 1025
Maladaptive Ex EWL 276
no EWL Maladaptive Ex 323
EWL Maladaptive Ex 395
Maladaptive Ex Maladaptive Ex 233
Table 8.5: Estimates of Transition Probabilities Across 1-year amongst Girls - Covariate Model contstraining direct transitions betwen No EWL and Maladaptive Ex groups: From (rows) - To (cols)
No EWL EWL Maladaptive Ex
No EWL 0.742 ( 0.719, 0.767 ) 0.226 ( 0.203, 0.248 ) 0.032 ( 0.027, 0.038 )
EWL 0.215 ( 0.19, 0.241 ) 0.617 ( 0.589, 0.645 ) 0.168 ( 0.145, 0.192 )
Maladaptive Ex 0.069 ( 0.055, 0.085 ) 0.38 ( 0.317, 0.444 ) 0.551 ( 0.475, 0.626 )
Table 8.6: Raw Number of Exercise State Transitions Amongst Boys
From To N
no EWL no EWL 2444
EWL no EWL 275
Maladaptive Ex no EWL 114
no EWL EWL 454
EWL EWL 222
Maladaptive Ex EWL 44
no EWL Maladaptive Ex 199
EWL Maladaptive Ex 94
Maladaptive Ex Maladaptive Ex 50
Table 8.7: Imputation Data
Variable Data_Type Method
Parent SES Ordinal PMM - Level 2
BMI Z-score (13) Continuous PMM - Level 2
Thin-ideal Internalization Z-score (14) Continuous PMM - Level 2
Body Dissatisfaction Z-score (14) Continuous PMM - Level 2
Fear of Weight Gain (14) Ordinal PMM - Level 2
Exercise for Weight Loss Ordinal 2-level PMM
Maladaptive Exercise Binary 2-level Binary

Note. PMM = ‘Predictive Mean Matching’

Table 8.8: Predictor Matrix for Multiple Imputation
id age_adjust driven_exercise exercise_wtloss bmi_z_bestavail ti_mean_14_std body_sat_mean_14_std fear_wtgain_14 parent_highest_occupation education_mum education_partner
id 0 0 1 1 1 1 1 1 1 0 0
age_adjust -2 0 1 1 1 1 1 1 1 0 0
driven_exercise -2 0 0 1 1 1 1 1 1 0 0
exercise_wtloss -2 0 1 0 1 1 1 1 1 0 0
bmi_z_bestavail -2 0 1 1 0 1 1 1 1 0 0
ti_mean_14_std -2 0 1 1 1 0 1 1 1 0 0
body_sat_mean_14_std -2 0 1 1 1 1 0 1 1 0 0
fear_wtgain_14 -2 0 1 1 1 1 1 0 1 0 0
parent_highest_occupation -2 0 1 1 1 1 1 1 0 1 1
education_mum -2 0 0 0 0 0 0 0 0 0 0
education_partner -2 0 0 0 0 0 0 0 0 0 0
Table 8.9: Missing Data Prior to Imputation - Girls
Variable Percent Missing Influx Outflux
Maladaptive Exercise 36.91 0.29 0.28
Exercise for Weight Loss 36.18 0.28 0.29
BMI Z - Age 13 17.33 0.12 0.59
Thin-ideal Internalization - Age 14 22.91 0.14 0.40
Body Satisifaction - Age 14 22.54 0.14 0.41
Fear of Wt Gain - Age 14 23.18 0.15 0.40
Parent SES 17.96 0.13 0.59
Table 8.10: Missing Data Prior to Imputation - Boys
Variable Percent Missing Influx Outflux
Maladaptive Exercise 45.61 0.38 0.22
Exercise for Weight Loss 45.37 0.38 0.22
BMI Z - Age 13 10.71 0.08 0.76
Thin-ideal Internalization - Age 14 24.17 0.17 0.45
Body Satisifaction - Age 14 20.19 0.13 0.50
Fear of Wt Gain - Age 14 21.27 0.14 0.49
Parent SES 13.25 0.10 0.71