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
|