Table 2 SELC 20 + 20 item level Rasch model location and fit statistics (complete cases only, n = 280). Sorted according to location within each subconstruct (from less to more self-efficacy)

Knowledge

 Tobacco and alcohol

  i2

Health effects of tobacco use

-1.192 (0.113)

0.050

1.506

0.826

  i7

Health effects of alcohol consumption

-1.039 (0.111)

0.357

6.154

0.188

  i1

Identification of tobacco use

-0.527 (0.104)

0.906

2.541

0.637

  i6

Identification of alcohol consumption

-0.123 (0.100)

0.565

1.631

0.803

  i3

Assessment of motivation for tobacco cessation

0.234 (0.099)

1.275

7.481

0.112

  i9

Advice about alcohol

0.371 (0.093)

-0.749

1.352

0.852

  i4

Advice about tobacco

0.393 (0.095)

-1.891

4.697

0.320

  i8

Assessment of motivation for decreased alcohol consumption

0.444 (0.110)

0.310

4.953

0.292

  i10

Motivational strategies for decreased alcohol consumption

0.616 (0.095)

-0.775

2.574

0.631

  i5

Motivational strategies for tobacco cessation

0.824 (0.100)

-0.149

5.996

0.199

 Physical activity

  i12

Health effects of physical activity

-0.912 (0.141)

0.854

8.602

0.072

  i11

Identification of physical activity

-0.579 (0.133)

1.388

1.385

0.847

  i14

Advice about physical activity

0.043 (0.122)

-2.964

15.156

0.004

  i15

Motivational strategies for physical activity

0.613 (0.118)

0.310

2.465

0.651

  i13

Assessment of motivation for physical activity

0.835 (0.125)

0.365

2.133

0.711

 Eating habits

  i17

Health effects of eating habits

-1.294 (0.133)

-0.298

8.218

0.084

  i19

Advice about eating habits

0.003 (0.116)

-1.301

6.656

0.155

  i16

Identification of eating habits

0.158 (0.118)

0.507

2.013

0.733

  i18

Assessment of motivation for healthier eating habits

0.431 (0.124)

0.914

3.347

0.501

  i20

Motivational strategies for healthy eating habits

0.703 (0.112)

-1.042

2.847

0.584

Knowledge

 Tobacco and alcohol

  i27

Health effects of alcohol consumption

-1.164 (0.110)

-0.725

3.339

0.503

  i22

Health effects of tobacco use

-1.114 (0.112)

-0.497

2.561

0.633

  i26

Identification of alcohol consumption

-0.282 (0.105)

0.785

3.540

0.471

  i24

Advice about tobacco

0.196 (0.100)

-0.851

3.809

0.432

  i39

Advice about alcohol

0.407 (0.098)

-1.744

2.416

0.660

  i23

Assessment of motivation for tobacco cessation

0.410 (0.101)

0.569

7.489

0.112

  i28

Assessment of motivation for decreased alcohol consumption

0.446 (0.106)

0.564

7.652

0.105

  i21

Identification of tobacco use

0.470 (0.103)

1.784

8.818

0.066

  i30

Motivational strategies for decreased alcohol consumption

0.771 (0.097)

-1.673

3.269

0.513

  i25

Motivational strategies for tobacco cessation

0.800 (0.101)

0.109

5.512

0.239

 Physical activity

  i32

Health effects of physical activity

-1.051 (0.136)

-0.721

14.712

0.005

  i31

Identification of physical activity

-0.442 (0.128)

1.425

5.747

0.219

  i34

Advice about physical activity

0.054 (0.127)

-2.183

6.941

0.139

  i33

Assessment of motivation for physical activity

0.622 (0.123)

0.796

8.712

0.082

  i35

Motivational strategies for physical activity

0.817 (0.115)

-0.876

7.469

0.113

 Eating habits

  i37

Health effects of eating habits

-1.210 (0.128)

-0.662

8.961

0.062

  i39

Advice about eating habits

-0.097 (0.119)

-1.042

7.023

0.135

  i36

Identification of eating habits

-0.073 (0.119)

1.307

4.629

0.327

  i38

Assessment of motivation for healthier eating habits

0.617 (0.125)

-1.051

7.843

0.097

  i40

Motivational strategies for healthy eating habits

0.764 (0.113)

-1.331

7.582

0.108