Table 3.

Multi-level model including and excluding main effect parameters.

Variable	Model 1 (Std. Error)	Model 2 (Std. Error)
Time spent in office chair	0.26 (0.06)*	0.25 (0.06)*
Lighting produces glare on screen	–0.40 (0.07)*	–0.39 (0.08)*
Chair comfort	–0.63 (0.08)*	–0.55 (0.08)*
Type of glasses, single-vision	–0.48 (0.18)*	–0.52 (0.18)*
Type of glasses, bi/trifocals	–0.66 (0.20)*	–0.66 (0.20)*
β1, Chair-and-training group	–0.67 (0.30)*	–0.39 (0.31)ns
β2, Training-only group	–0.88 (0.33)*	–0.82 (0.34)*
β3, Intervention phase	–0.06 (0.07)ns	0.18 (0.12)ns
β4, Chair*intervention	–	–0.49 (0.15)*
β5, Training*intervention	–	–0.13 (0.17)ns
β0, Intercept term	1.71 (0.44)	1.77 (0.45)
εij, Level 1 variance	2.48 (0.07)	2.47 (0.07)
uj, Level 2 variance	2.56 (0.29)	2.58 (0.29)
Model –2 ln (likelihood)	12068.01	12055.61
Difference in –2 ln (likelihoods) = 12.40*

^*p < 0.05

^nsp > 0.05.