Table 2 Fitting the smoking status time-varying coefficient model

Selection of variables that have varying coefficients

LM

logistic model

<1

-

-

206590.4

21.00

Model age

LM + s(t):age

4.7

<0.001

LM

206554.4

28.88

Model alcohol

LM + s(t):alcohol use

2.1

<0.001

LM

206566.0

27.39

Model physical

LM + s(t):physical activity

2.1

<0.001

LM

206570.1

26.19

Model income

LM + s(t):income

2.2

<0.001

LM

206574.8

26.33

Model mstatus

LM + s(t):martital status

2.1

<0.001

LM

206573.8

26.50

Model edu

LM + s(t):education

3.1

<0.001

LM

206573.2

26.26

Model sex

LM + s(t):sex

1.4

<0.001

LM

206572.4

25.37

Model work

LM + s(t):work status

1.4

<0.001

LM

206575.2

25.08

Model region

LM + s(t):region

2.2

<0.001

LM

206573.2

26.81

Model depress

LM + s(t):depression status

1.4

<0.001

LM

206574.2

24.49

Model time

LM + s(t)

1.6

<0.001

LM

206572.7

23.72

Finding the full varying coefficient model

Model I

Model age + s(t):alcohol use

8.9

0.008

Model age

206548.7

33.21

Model II

Model I + s(t):physical activity

16.8

0.070

Model I

206547.6

36.40

Model III

Model II + s(t):income

25.7

0.261

Model II

206549.0

38.45

Model IV

Model II + s(t):marital status

24.4

0.539

Model II

206550.8

38.72

Model V

Model II + s(t):education

36.5

0.227

Model II

206549.4

39.48

Model VI

Model II + s(t):sex

24.4

0.125

Model II

206547.3

37.34

Model VII

Model II + s(t):work status

21.4

0.550

Model II

206549.3

27.38

Model VIII

Model II + s(t):region

26.5

0.470

Model II

206550.0

38.32

Model IX

Model II + s(t):depression status

22.0

0.369

Model II

206548.9

37.42

Model X

Model I + s(t)

10.4

0.006

Model I

206548.7

33.21

Notes: s(t) - spline of time