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. Author manuscript; available in PMC: 2016 Jun 21.
Published in final edited form as: Psychol Addict Behav. 2016 Mar 14;30(4):484–493. doi: 10.1037/adb0000165

Table 2.

Results from mixed-effects location-scale analyses predicting negative mood from NDSS scores and covariates.

Base Model
Smoking Frequency Covaried
Model/Predictor Mean Level
WS-WW Variance
Mean Level
WS-WW Variance
b SE P VR SE P b SE P VR SE P
All Records
Intercept 3.56 0.20 < .001 2.42 0.23 < .001 3.23 0.22 < .001 2.16 0.23 < .001
Gender −0.34 0.15 .021 0.82 0.06 .004 −0.30 0.15 .044 0.83 0.06 .010
10th Grade −0.02 0.15 .873 0.94 0.07 .411 0.04 0.15 .771 0.96 0.07 .560
Time −0.27 0.07 < .001 0.78 0.02 < .001 −0.26 0.07 < .001 0.79 0.02 < .001
BS NDSS 0.15 0.10 .149 1.14 0.05 .004 0.68 0.18 < .001 1.37 0.12 < .001
WS NDSS 0.17 0.06 .011 1.09 0.02 < .001 0.24 0.08 .003 1.12 0.03 < .001
BS Smoking -- -- -- -- -- -- −0.18 0.05 < .001 0.94 0.02 .017
WS Smoking -- -- -- -- -- -- −0.03 0.02 .141 0.99 0.01 .175
Random Prompts
Intercept 3.53 .020 < .001 2.41 0.24 < .001 3.20 0.22 < .001 2.06 0.23 < .001
Gender −0.34 0.15 .024 0.79 0.06 .001 −0.29 0.15 .049 0.80 0.06 .004
10th Grade −0.03 0.15 .852 0.93 0.07 .310 0.04 0.15 .789 0.95 0.07 .507
Time −0.24 0.07 < .001 0.82 0.02 < .001 −0.22 0.07 .001 0.82 0.02 < .001
BS NDSS 0.15 0.10 .134 1.12 0.06 .024 0.38 0.19 < .001 1.44 0.13 < .001
WS NDSS 0.18 0.07 .007 1.08 0.02 < .001 0.24 0.08 .003 1.09 0.03 < .001
BS Smoking -- -- -- -- -- -- −0.18 0.05 < .001 0.92 0.01 .002
WS Smoking -- -- -- -- -- -- −0.02 0.02 .257 1.00 0.001 .626

Note: BS = between-subjects, WS = within-subjects WS-WW = within-subjects, within-wave, VR = variance ratio. WS-WW variance parameters were estimated using a log-linear model and then exponentiated so that they represent variance ratios (i.e., the ratio of WS-WW variance per one-unit change on the covariate).