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Table 2 Mixed effect models with the best fractional polynomial function for childhood BMI trajectory, by model degreea

From: Childhood body mass index trajectories: modeling, characterizing, pairwise correlations and socio-demographic predictors of trajectory characteristics

Degree

No. of candidate models

Included age terms in the mixed effect model with the best fractional polynomial function

Goodness of fit (smaller is better)b

  

Age(-2)

Age(-1)

Age(-0.5)

log(Age)

Age0.5

Age

Age2

Age3

-2 Log likelihood

BIC

Boys (N = 1,680)

           

3 rd degree

56

   

×

×

×

  

150196

150218

4th degree

70

 

×

 

×

×

×

  

149688

149710

5th degree

56

×

×

×

×

×

   

147836

147858

6th degree

28

×

×

×

×

×

×

  

148889

148911

7th degree

8

×

×

×

×

×

×

×

 

161668

161690

8th degree

1

×

×

×

×

×

×

×

×

166173

166181

Girls (N = 1,609)

           

3 rd degree

56

   

×

×

×

  

141787

141809

4th degree

70

 

×

×

×

×

   

139990

140012

5th degree

56

×

×

×

×

×

   

138131

138153

6th degree

28

×

×

×

×

×

×

  

140079

140101

7th degree

8

×

×

×

×

×

×

×

 

152402

152424

8th degree

1

×

×

×

×

×

×

×

×

156241

156248

  1. BIC, Bayesian information criterion
  2. a Data from 3,289 children with at least 18 well-child visits from age 1 week to 18 years
  3. b The best-fitting models are in bold font