Table 4

Multilevel Modeling Analyses Predicting Health Behavior after an Intervention and the Cross-Level Interaction between Individual Characteristics and Times

Baseline

Pre-intervention Change from Baseline

Post-intervention Change from Baseline

Within-Subject Fixed Effects

Parameter

Coeff.

SE

Parameter

Coeff.

SE

Parameter

Coeff.

SE

Occurrence of exercise

Intercept

γ₀₀

1.66

.15

γ₁₀

-.39

.09

γ₂₀

-.30

.09

Group

γ₀₁

.07

.20

γ₁₁

.25

.11

γ₂₁

.58*

.11

Variety of exercises

Intercept

γ₀₀

.40

.13

γ₁₀

-.25

.19

γ₂₀

-.14

.19

Group

γ₀₁

-.07

.17

γ₁₁

.22

.24

γ₂₁

.43*

.24

- Occurrence of stretching

Intercept

γ₀₀

.56

.19

γ₁₀

-.27

.14

γ₂₀

-.18

.14

Group

γ₀₁

.19

.24

γ₁₁

.11

.18

γ₂₁

.67*

.17

- Occurrence of walking

Intercept

γ₀₀

.56

.22

γ₁₀

-.49

.14

γ₂₀

-.72

.16

Group

γ₀₁

-.22

.29

γ₁₁

.41

.19

γ₂₁

.76*

.21

- Occurrence of strengthening exercises

Intercept

γ₀₀

-.48

.29

γ₁₀

-.42

.19

γ₂₀

.05

.18

Group

γ₀₁

.60

.37

γ₁₁

.20

.24

γ₂₁

.14

.22

- Occurrence of relaxation activities

Intercept

γ₀₀

1.17

.26

γ₁₀

-.15

.09

γ₂₀

-.20

.09

Group

γ₀₁

-.89

.35

γ₁₁

.54

.13

γ₂₁

.79*

.13

Variety of relaxation activities

Intercept

γ₀₀

.07

.18

γ₁₀

-.17

.19

γ₂₀

-.09

.20

Group

γ₀₁

-.69

.26

γ₁₁

.60

.29

γ₂₁

.60

.22

Occurrence of leisure activities

Intercept

γ₀₀

1.67

.12

γ₁₀

.35

.08

γ₂₀

.23

.09

Group

γ₀₁

.09

.15

γ₁₁

-.34

.11

γ₂₁

-.29

.12

Variety of leisure activities

Intercept

γ₀₀

.17

.14

γ₁₀

.37

.18

γ₂₀

.29

.19

Group

γ₀₁

.05

.18

γ₁₁

-.27

.24

γ₂₁

-.07*

.25

Variety of everyday coping behaviors

Intercept

γ₀₀

2.14

.06

γ₁₀

-.00

.07

γ₂₀

.09

.07

Group

γ₀₁

-.02

.07

γ₁₁

.05

.09

γ₂₁

.02

.09

Social networks

Intercept

γ₀₀

6.48

.28

γ₁₀

-.46

.18

γ₂₀

-.09

.19

Group

γ₀₁

-.16

.37

γ₁₁

.25

.24

γ₂₁

.29

.26

* p < .05

Significance of coefficient γ₂₁ is indicative of intervention effects using the following model:

Level 1 model: Outcome = β_0j + β_1jX₁ + β_2jX₂+ r_ij

Level 2 model: T₁ β_0j = γ₀₀ + γ₀₁ Gr_j + u_oj

T₂ β_1j = γ₁₀ + γ₁₁ Gr_j

T₃ β_2j = γ₂₀ + γ₂₁ Gr_j

Meaning of Coefficients:

γ₀₀ = Predicted value in outcome variable at baseline for participants in control group

γ₀₁ Gr_j = Predicted difference in outcome variable at baseline for participants in experimental group

γ₁₀ = Predicted change in outcome variable from baseline to pre-intervention for participants in control group

γ₁₁ Gr_j = Predicted difference in change in outcome variable from baseline to pre-intervention for participants in experimental group

γ₂₀ = Predicted change in outcome variable from baseline to post-intervention for participants in control

γ₂₁ Gr_j = Predicted difference in change in outcome variable from baseline to post-intervention for participants in experimental group.

where i: 1 .....N individuals ; r_ij: level 1 error term ; γ : parameter coefficients ; u_oj: level-2 random effect ; β: coefficient; Gr: group membership (1 = experimental, 0 = control) ; X₁: dummy variable (1 = pre-intervention, 0 = otherwise) ; X₂: dummy variable(1 = post-intervention, 0 = otherwise)

Nour et al. International Journal of Behavioral Nutrition and Physical Activity 2006 3:12   doi:10.1186/1479-5868-3-12