Negative affect. A significantly ( p .01) positive main effect
of temperature ( 0.035) and negative main effects of wind
power (0.023) and sunlight (0.023) on negative affect
were found to be significant in the multivariate linear mixed-model
analysis with fixed effects. Interestingly, these main effects were
not found in the univariate linear mixed-model analyses, indicating
that the positive effect of temperature initially suppressed the
negative effect of sunlight.
The variance between individuals in the effects of weather on
negative affect was found to be significant ( p .01) for all variables
except for precipitation. Thus, the effects of all weather parameters on
negative affect differed between individuals. Interestingly, the random
variance around the slope of the (nonsignificant) photoperiod effect
(2 .166) was more than three times higher than the random
variance around the other slopes (2 .050).
Tiredness. In the multivariate mixed-model analysis with
fixed effects, a significantly ( p .01) negative main effect of
sunlight on tiredness was found ( 0.063). The results of the
univariate mixed-model analyses with random effects also yield a
significant main effect of sunlight ( 0.065). In addition,
univariate mixed-model analyses showed main effects of precipitation
( 0.032) and air pressure ( 0.071).
The absence of these main effects in the multivariate analysis
suggests that the effects of precipitation and air pressure were
partly dependent on the effect of sunlight. To test whether the
effects of precipitation and air pressure were mediated by the
variable sunlight, a mediation analysis was conducted (Baron &
Kenny, 1986). First, the unique effects of precipitation and air
pressure on tiredness were found to be significant, but disappeared
when controlling for sunlight (see Table 2). Second, the association
between sunlight and tiredness was significant (see Table 2),
with more sunlight being associated with less tiredness. Finally,
the negative association between precipitation and sunlight and the
positive association between air pressure and sunlight was significant
(see Table 1). Therefore, it can be concluded that sunlight
significantly mediated the effects of precipitation and air pressure
on tiredness.
The random-effects analyses revealed significant ( p .01)
random slope variance between individuals in the effects of all
weather variables on tiredness, except for wind power. These
findings suggest that the effects of weather on tiredness differ
between individuals. Notably, the between-person variance around
the slope of photoperiod was again much higher than the variance
around the slope of the other weather variables.
Sedang diterjemahkan, harap tunggu..
