Results

Classical Process Model

Model summary
  AIC BIC Log-likelihood n df
Model 1 4160.444 4186.496 -2070.222 100 0
R-squared
R²
  Model 1
wakefulness 0.989

Path plots

Model 1

Conceptual path plot

Parameter estimates

Important : Parameter estimates can only be interpreted as causal effects if all confounding effects are accounted for and if the causal effect directions are correctly specified.

Model 1

Path coefficients
95% Confidence Interval
      Estimate Std. Error z-value p Lower Upper
hours.awake → wakefulness 23.013 0.344 66.911 < .001 22.339 23.687
ml.coffee → wakefulness 1.269 0.020 63.595 < .001 1.230 1.309
hours.awake:ml.coffee → wakefulness 0.102 0.004 25.895 < .001 0.095 0.110
Note.  Moderation effect estimates are based on mean-centered variables.
Direct and indirect effects
95% Confidence Interval
      ml.coffee Estimate Std. Error z-value p Lower Upper
hours.awake → wakefulness 16 13.651 0.511 26.699 < .001 12.649 14.653
hours.awake → wakefulness 50 23.635 0.344 68.791 < .001 22.961 24.308
hours.awake → wakefulness 84 32.713 0.496 65.992 < .001 31.741 33.684
Note.  Moderation effect estimates are based on mean-centered variables.
Total effects
95% Confidence Interval
        ml.coffee Estimate Std. Error z-value p Lower Upper
Total hours.awake → wakefulness 16 13.651 0.511 26.699 < .001 12.649 14.653
  hours.awake → wakefulness 50 23.635 0.344 68.791 < .001 22.961 24.308
  hours.awake → wakefulness 84 32.713 0.496 65.992 < .001 31.741 33.684
Note.  Moderation effect estimates are based on mean-centered variables.

Linear Regression

Model Summary - wakefulness
Model R R² Adjusted R² RMSE R² Change df1 df2 p
M₀ 0.000 0.000 0.000 163.406 0.000 0 99  
M₁ 0.955 0.912 0.910 48.893 0.912 2 97 < .001
M₂ 0.994 0.989 0.988 17.705 0.076 1 96 < .001
Note.  M₁ includes hours.awake, ml.coffee
Note.  M₂ includes hours.awake, ml.coffee, hours.awake:ml.coffee
ANOVA
Model   Sum of Squares df Mean Square F p
M₁ Regression 2.412e+6 2 1.206e+6 504.412 < .001
  Residual 231876.234 97 2390.477    
  Total 2.643e+6 99      
M₂ Regression 2.613e+6 3 871118.347 2779.123 < .001
  Residual 30091.281 96 313.451    
  Total 2.643e+6 99      
Note.  M₁ includes hours.awake, ml.coffee
Note.  M₂ includes hours.awake, ml.coffee, hours.awake:ml.coffee
Note.  The intercept model is omitted, as no meaningful information can be shown.
Coefficients
Model   Unstandardized Standard Error Standardized t p
M₀ (Intercept) 353.775 16.341   21.650 < .001
M₁ (Intercept) -194.227 18.475   -10.513 < .001
  hours.awake 23.458 0.968 0.730 24.229 < .001
  ml.coffee 1.224 0.056 0.658 21.838 < .001
M₂ (Intercept) 61.683 12.103   5.096 < .001
  hours.awake -3.612 1.123 -0.112 -3.216 .002
  ml.coffee 0.266 0.043 0.143 6.197 < .001
  hours.awake  ✻   ml.coffee 0.102 0.004 1.001 25.372 < .001

Residuals vs. Predicted

Q-Q Plot Standardized Residuals

Descriptives Plots

hours.awake - wakefulness