. 2023 Jan 14;13:773. doi: 10.1038/s41598-022-26663-4

Table 1.

Results of the multilevel linear models regressing love components (i.e., STLS-45, intimacy, passion, and commitment) on countries’ levels of Human Development Index (HDI), Collectivism level, annual average temperature, and participants’ sex and length of relationship (in months), with participants nested within countries.

	STLS-45				Intimacy				Passion				Commitment
	β	SE	95% CI	p	β	SE	95% CI	p	β	SE	95% CI	p	β	SE	95% CI	p
Fixed effects
HDI^a	0.233	0.043	[0.043, 0.148]	< 0.001***	0.312	0.046	[0.046, 0.221]	< 0.001***	0.143	0.049	[0.049, 0.047]	0.004**	0.215	0.039	[0.039, 0.139]	< 0.001***
Collectivism^b	0.074	0.033	[0.033, 0.010]	0.023*	0.094	0.035	[0.035, 0.026]	0.007**	0.054	0.037	[0.037, − 0.018]	0.145	0.059	0.029	[0.029, 0.001]	0.045*
Temperature^c	0.099	0.035	[0.035, 0.031]	0.004**	0.084	0.037	[0.037, 0.012]	0.023*	0.118	0.039	[0.039, 0.041]	0.003**	0.077	0.031	[0.031, 0.016]	0.014*
Sex^d	− 0.016	0.011	[0.011, − 0.038]	0.152	0.027	0.011	[0.011, 0.006]	0.012*	− 0.042	0.011	[0.011, − 0.064]	< 0.001***	− 0.022	0.011	[0.011, − 0.043]	0.055
Relationship length^e	− 0.01	0.011	[0.011, − 0.032]	0.363	− 0.025	0.011	[0.011, − 0.046]	0.021*	− 0.076	0.011	[0.011, − 0.098]	< 0.001***	0.081	0.011	[0.011, 0.059]	< 0.001***
Random effects
Variance	0.030				0.035				0.042				0.023
Variance SD	0.174				0.188				0.205				0.150
ICC	0.035				0.043				0.045				0.026
Pseudo r²	0.032				0.065				0.021				0.035
df_residuals	7532				7532				7524				7459
Deviance	20,192				19,720.7				20,612.6				20,081.5

*p < 0.05, **p < 0.01, ***p < 0.001. ^aHuman Development Index, ^bCollectivism-in-group favoritism, ^cTemperature–Average annual temperatures, ^dParticipants’ sex with men as a reference group, ^eParticipants’ relationship length in months.