Table 3.

Results of Linear Mixed-Effects Model

Random effects: ∼1|ID
	(Intercept)	Residual
SD	79.94	81.53

Fixed effects: CIT ∼ fT4 + TEMP30D
	Value	Std. Error	DF	t-Value	p-Value
(Intercept)	80.54	46.07	32	1.75	0.090
fT4	6.02	2.46	31	2.44	0.021
TEMP30D	–6.01	1.65	31	–3.64	0.001

In order to assess the effects of thyroid hormone levels on CIT at both study visits (repeated measures), a linear mixed-effects model with a random intercept was fitted to the data. CIT was inserted as the response variable. fT4 and TEMP30D (outdoor temperature during the 30 days preceding the visit) were entered as fixed-effect variables. The individual study participant was inserted as a random-effect variable (random intercept).

CIT, cold-induced thermogenesis.