Table 4 Results of mixed-effects logistic regressions investigating selection homophily effects: (1) for friendship nominations at baseline; (2) for adding friends between baseline and follow-up; or (3) for dropping friends between baseline and follow-up.

From: Selection homophily and peer influence for adolescents’ smoking and vaping norms and outcomes in high and middle-income settings

Outcomes	Time-point	(1) Baseline friend nominations					(2) Adding friends from the school year group					(3) Dropping friends from the school year group
		Original scale			Re-scaled (0–10)	ICC^c	Original scale			Re-scaled (0–10)	ICC^c	Original scale			Re-scaled (0–10)	ICC^c
		n	OR (SE)^a	p-value	OR (SE)^b	ICC^c	n	OR (SE)^a	p-value	OR (SE)^b	ICC^c	n	OR (SE)^a	p-value	OR (SE)^b	ICC^c
Experiment Part 2: Injunctive norms for smoking/vaping (−1 = “extremely socially inappropriate” to +1 = “extremely socially appropriate”).
P2S2	t = base	106,804	0.99 (0.04)	0.78	0.998 (0.008)	0.015	99,869	0.81 (0.07)	0.01	0.96 (0.02)	0.081	6935	0.78 (0.08)	0.02	0.95 (0.02)	0.140
P2S2	t = fu						100,298	0.91 (0.06)	0.20	0.98 (0.01)	0.079	6858	0.86 (0.08)	0.10	0.97 (0.02)	0.130
P2S3	t = base	106,644	0.98 (0.04)	0.55	0.995 (0.008)	0.015	99,723	0.93 (0.06)	0.29	0.99 (0.01)	0.083	6921	1.04 (0.09)	0.68	1.007 (0.02)	0.142
P2S3	t = fu						100,455	1.04 (0.07)	0.52	1.009 (0.01)	0.080	6865	1.12 (0.10)	0.21	1.02 (0.02)	0.132
P2S4	t = base	106,804	0.99 (0.03)	0.77	0.998 (0.006)	0.015	99,869	0.94 (0.05)	0.30	0.99 (0.01)	0.082	6935	1.01 (0.07)	0.89	1.002 (0.01)	0.142
P2S4	t = fu						100,087	0.96 (0.06)	0.51	0.99 (0.01)	0.080	6847	1.14 (0.09)	0.12	1.03 (0.02)	0.130
P2S5	t = base	106,804	0.94 (0.03)	0.07	0.99 (0.007)	0.015	99,869	0.90 (0.06)	0.08	0.98 (0.01)	0.082	6935	1.17 (0.08)	0.04	1.03 (0.02)	0.142
P2S5	t = fu						100,455	0.94 (0.06)	0.32	0.99 (0.01)	0.080	6865	1.19 (0.09)	0.02	1.04 (0.02)	0.132
P2S6	t = base	106,478	0.92 (0.03)	0.02	0.98 (0.007)	0.015	99,578	0.93 (0.05)	0.20	0.99 (0.01)	0.083	6900	0.88 (0.06)	0.07	0.97 (0.01)	0.145
P2S6	t = fu						100,061	0.94 (0.06)	0.30	0.99 (0.01)	0.081	6847	0.999 (0.07)	0.99	0.9998 (0.01)	0.132
P2S7	t = base	106,804	0.81 (0.03)	<0.001^f	0.96 (0.007)	0.015	99,869	0.84 (0.05)	0.004	0.97 (0.01)	0.082	6935	0.98 (0.07)	0.75	0.995 (0.01)	0.142
P2S7	t = fu						100,298	0.94 (0.06)	0.30	0.99 (0.01)	0.080	6858	1.31 (0.10)	0.001	1.06 (0.02)	0.129
P2S8	t = base	106,804	0.82 (0.03)	<0.001^f	0.96 (0.007)	0.015	99,869	0.73 (0.05)	<0.001^f	0.94 (0.01)	0.082	6935	1.01 (0.08)	0.89	1.002 (0.02)	0.142
P2S8	t = fu						100,455	0.82 (0.05)	0.001	0.96 (0.01)	0.080	6865	0.97 (0.08)	0.74	0.99 (0.02)	0.132
P2S9	t = base	106,804	0.92 (0.04)	0.04	0.98 (0.008)	0.015	99,869	0.89 (0.06)	0.05	0.98 (0.01)	0.082	6935	0.95 (0.08)	0.56	0.99 (0.02)	0.142
P2S9	t = fu						100,298	0.90 (0.06)	0.14	0.98 (0.01)	0.080	6858	1.16 (0.10)	0.08	1.03 (0.02)	0.134
Experimental injunctive norms scale (average P2S2–P2S9)	t = base	106,318	0.80 (0.05)	0.001	0.96 (0.01)	0.015	99,432	0.66 (0.08)	0.001	0.92 (0.02)	0.082	6886	0.95 (0.13)	0.71	0.99 (0.03)	0.144
Experimental injunctive norms scale (average P2S2–P2S9)	t = fu						99,387	0.82 (0.09)	0.06	0.96 (0.02)	0.079	6815	1.32 (0.19)	0.05	1.06 (0.03)	0.131
Experiment Part 3: Descriptive norms for smoking/vaping (−1 = “none of my peers” to +1 = “all of my peers”).
P3Q1	t = base	106,804	0.84 (0.03)	<0.001^f	0.97 (0.006)	0.014	99,869	0.89 (0.04)	0.03	0.98 (0.01)	0.081	6935	1.06 (0.07)	0.35	1.01 (0.01)	0.143
P3Q1	t = fu						100,455	0.96 (0.04)	0.34	0.99 (0.009)	0.080	6865	1.20 (0.07)	0.002	1.04 (0.01)	0.132
P3Q2	t = base	106,644	0.85 (0.02)	<0.001^f	0.97 (0.006)	0.014	99,712	0.98 (0.05)	0.69	0.996 (0.009)	0.082	6932	1.02 (0.06)	0.75	1.004 (0.01)	0.143
P3Q2	t = fu						100,455	0.93 (0.04)	0.11	0.99 (0.009)	0.080	6865	1.19 (0.07)	0.003	1.04 (0.01)	0.133
Experimental descriptive norms scale (average P3Q1−P3Q2)	t = base	106,644	0.82 (0.03)	<0.001^f	0.96 (0.007)	0.014	99,712	0.94 (0.05)	0.25	0.99 (0.01)	0.081	6932	0.99 (0.07)	0.87	0.998 (0.01)	0.142
Experimental descriptive norms scale (average P3Q1−P3Q2)	t = fu						100,455	0.93 (0.05)	0.17	0.99 (0.01)	0.080	6865	1.18 (0.08)	0.009	1.03 (0.01)	0.133
Experiment Part 4: Willingness to pay to support anti-smoking norms (Donations to ASSIST/Dead Cool; 0 = “0 tokens donated” to 10 = “10 tokens donated”)
Donation to ASSIST/Dead Cool	t = base	106,640	0.97 (0.006)	<0.001^f	0.97 (0.006)	0.016	99,718	0.97 (0.009)	0.006	0.97 (0.009)	0.083	6922	0.999 (0.01)	0.91	0.999 (0.01)	0.143
Donation to ASSIST/Dead Cool	t = fu						100,218	0.98 (0.01)	0.03	0.98 (0.01)	0.080	6854	1.02 (0.01)	0.15	1.02 (0.01)	0.131
Self-report injunctive smoking norms (−2 = “think(s) that I definitely should smoke” to +2 = “think(s) that I definitely should not smoke”).
IN1	t = base	113,380	0.96 (0.02)	0.02	0.98 (0.007)	0.017	106,099	1.0009 (0.03)	0.98	1.0004 (0.01)	0.082	7281	1.06 (0.04)	0.11	1.02 (0.01)	0.139
IN1	t = fu						105,871	0.998 (0.02)	0.92	0.999 (0.01)	0.081	7263	1.06 (0.03)	0.06	1.02 (0.01)	0.135
IN2	t = base	113,642	0.92 (0.02)	0.001	0.97 (0.01)	0.017	106,348	1.04 (0.05)	0.34	1.02 (0.02)	0.081	7294	1.07 (0.06)	0.28	1.03 (0.02)	0.139
IN2	t = fu						105,952	0.99 (0.04)	0.75	0.995 (0.01)	0.080	7276	1.10 (0.05)	0.04	1.04 (0.02)	0.133
IN3	t = base	113,320	0.94 (0.01)	<0.001^f	0.98 (0.006)	0.016	106,056	0.995 (0.03)	0.86	0.998 (0.01)	0.081	7264	1.13 (0.04)	0.001	1.05 (0.01)	0.134
IN3	t = fu						105,786	1.01 (0.02)	0.54	1.006 (0.01)	0.080	7266	1.09 (0.03)	0.007	1.03 (0.01)	0.134
IN4	t = base	113,044	0.97 (0.01)	0.05	0.99 (0.005)	0.017	105,786	1.008 (0.02)	0.72	1.003 (0.009)	0.082	7258	1.04 (0.03)	0.23	1.01 (0.01)	0.140
IN4	t = fu						105,786	0.996 (0.02)	0.87	0.998 (0.009)	0.081	7266	1.06 (0.03)	0.04	1.02 (0.01)	0.136
IN5	t = base	113,218	0.95 (0.01)	<0.001^f	0.98 (0.005)	0.016	105,953	0.97 (0.02)	0.19	0.99 (0.009)	0.083	7265	1.03 (0.03)	0.33	1.01 (0.01)	0.140
IN5	t = fu						105,786	0.99 (0.02)	0.66	0.996 (0.009)	0.080	7266	1.02 (0.03)	0.58	1.006 (0.01)	0.136
IN6	t = base	113,480	0.92 (0.01)	<0.001^f	0.97 (0.006)	0.016	106,205	0.96 (0.02)	0.07	0.98 (0.009)	0.082	7275	1.12 (0.03)	<0.001^f	1.05 (0.01)	0.136
IN6	t = fu						105,786	0.98 (0.02)	0.49	0.99 (0.009)	0.081	7266	1.14 (0.04)	<0.001^f	1.05 (0.01)	0.131
IN7	t = base	113,480	0.94 (0.01)	<0.001^f	0.98 (0.006)	0.017	106,205	0.97 (0.02)	0.24	0.99 (0.009)	0.082	7275	1.17 (0.03)	<0.001^f	1.07 (0.01)	0.135
IN7	t = fu						105,952	0.97 (0.02)	0.17	0.99 (0.009)	0.080	7276	1.15 (0.03)	<0.001^f	1.06 (0.01)	0.130
Self-report injunctive norms scale (average IN1–IN7)	t = base	113,480	0.94 (0.01)	<0.001^f	0.94 (0.01)	0.016	105,390	0.997 (0.05)	0.95	0.999 (0.02)	0.082	7234	1.25 (0.08)	<0.001^f	1.09 (0.03)	0.135
Self-report injunctive norms scale (average IN1–IN7)	t = fu						105,622	0.99 (0.04)	0.86	0.997 (0.02)	0.081	7254	1.21 (0.07)	0.001	1.08 (0.02)	0.133
Self-report descriptive smoking norms (DN1: 1 = “smoke(s) very often” to 5 = “never smoke(s)”/“don’t know”; DN2: 1 = “almost all of them smoke” to 5 = “almost none of them smoke”/“don’t know”).
DN1.1	t = base	113,544	0.94 (0.02)	<0.001^f	0.97 (0.007)	0.016	106,253	0.98 (0.02)	0.41	0.99 (0.01)	0.081	7291	1.21 (0.05)	<0.001^f	1.08 (0.02)	0.135
DN1.1	t = fu						106,201	0.98 (0.02)	0.30	0.99 (0.009)	0.080	7285	1.18 (0.04)	<0.001^f	1.07 (0.01)	0.136
DN1.2	t = base	113,806	0.96 (0.01)	<0.001	0.98 (0.004)	0.017	106,505	0.97 (0.02)	0.09	0.99 (0.007)	0.081	7301	1.009 (0.02)	0.67	1.004 (0.009)	0.140
DN1.2	t = fu						106,201	1.001 (0.02)	0.96	1.0004 (0.007)	0.081	7285	1.02 (0.02)	0.47	1.01 (0.01)	0.135
DN1.3	t = base	113,642	0.97 (0.009)	0.001	0.99 (0.004)	0.017	106354	1.006 (0.02)	0.72	1.002 (0.006)	0.081	7288	0.98 (0.02)	0.37	0.99 (0.008)	0.140
DN1.3	t = fu						106,201	1.004 (0.02)	0.80	1.002 (0.006)	0.081	7285	1.002 (0.02)	0.94	1.0007 (0.008)	0.135
DN1.4	t = base	113,544	0.99 (0.01)	0.40	0.996 (0.005)	0.017	106,253	0.99 (0.02)	0.67	0.996 (0.009)	0.082	7291	1.03 (0.03)	0.36	1.01 (0.01)	0.139
DN1.4	t = fu						106,201	0.98 (0.02)	0.38	0.99 (0.008)	0.080	7285	1.02 (0.03)	0.40	1.008 (0.01)	0.135
DN1.5	t = base	113,544	0.995 (0.01)	0.73	0.998 (0.005)	0.017	106,253	1.02 (0.02)	0.41	1.008 (0.01)	0.082	7291	1.09 (0.03)	0.004	1.04 (0.01)	0.138
DN1.5	t = fu						106,201	1.02 (0.02)	0.38	1.008 (0.009)	0.080	7285	1.06 (0.04)	0.07	1.02 (0.01)	0.134
Self-report descriptive norms scale 1 (average DN1.1–DN1.5)	t = base	113,120	0.86 (0.02)	<0.001^f	0.94 (0.009)	0.017	105,852	0.92 (0.04)	0.03	0.97 (0.02)	0.081	7268	1.08 (0.06)	0.14	1.03 (0.02)	0.138
Self-report descriptive norms scale 1 (average DN1.1–DN1.5)	t = fu						106,201	0.98 (0.03)	0.46	0.99 (0.01)	0.080	7285	1.10 (0.06)	0.07	1.04 (0.02)	0.134
DN2.1	t = base	113806	0.88 (0.02)	<0.001^f	0.95 (0.007)	0.016	106505	1.02 (0.03)	0.55	1.006 (0.01)	0.081	7301	1.26 (0.05)	<0.001^f	1.10 (0.02)	0.137
DN2.1	t = fu						106,201	0.98 (0.03)	0.43	0.99 (0.01)	0.081	7285	1.15 (0.04)	<0.001^f	1.06 (0.02)	0.134
DN2.2	t = base	113,806	0.97 (0.01)	0.03	0.99 (0.005)	0.017	106,505	1.002 (0.02)	0.92	1.0009 (0.009)	0.081	7301	1.03 (0.03)	0.25	1.01 (0.01)	0.140
DN2.2	t = fu						106,045	0.97 (0.02)	0.15	0.99 (0.008)	0.081	7275	0.97 (0.03)	0.37	0.99 (0.01)	0.135
DN2.3	t = base	113,806	0.90 (0.02)	<0.001^f	0.96 (0.008)	0.016	106,505	0.97 (0.03)	0.31	0.99 (0.01)	0.081	7301	1.04 (0.04)	0.37	1.02 (0.02)	0.140
DN2.3	t = fu						106,201	0.95 (0.03)	0.08	0.98 (0.01)	0.080	7285	0.999 (0.04)	0.97	0.999 (0.02)	0.135
Self-report descriptive norms scale 2 (average DN2.1–DN2.3)	t = base	113,806	0.85 (0.02)	<0.001^f	0.94 (0.01)	0.016	106,505	0.96 (0.04)	0.30	0.98 (0.02)	0.081	7301	1.24 (0.07)	<0.001^f	1.09 (0.02)	0.137
Self-report descriptive norms scale 2 (average DN2.1–DN2.3)	t = fu						106,045	0.94 (0.04)	0.09	0.97 (0.01)	0.081	7275	1.08 (0.06)	0.17	1.03 (0.02)	0.135
Self-report smoking behavior, intentions, knowledge, attitudes, and psycho-social antecedents, and objectively measured smoking behavior^d
Self-report smoking behavior (1– 4)	t = base	114,672	0.91 (0.02)	<0.001^f	0.97 (0.006)	0.016	107326	0.98 (0.03)	0.52	0.99 (0.009)	0.081	7346	1.23 (0.05)	<0.001^f	1.07 (0.01)	0.136
Self-report smoking behavior (1– 4)	t = fu						107,326	1.02 (0.03)	0.49	1.006 (0.008)	0.082	7346	1.25 (0.05)	<0.001^f	1.07 (0.01)	0.133
Intentions (1–6)	t = base	113,856	0.95 (0.01)	<0.001^f	0.97 (0.006)	0.016	106,569	1.01 (0.02)	0.59	1.005 (0.009)	0.082	7287	1.04 (0.03)	0.11	1.02 (0.01)	0.138
Intentions (1–6)	t = fu						106,791	0.98 (0.02)	0.17	0.99 (0.008)	0.081	7311	1.10 (0.03)	<0.001^f	1.05 (0.01)	0.136
Knowledge (0–6)	t = base	114,328	0.98 (0.01)	0.12	0.99 (0.006)	0.017	107,005	0.98 (0.02)	0.15	0.99 (0.01)	0.082	7323	1.002 (0.02)	0.93	1.001 (0.01)	0.139
Knowledge (0–6)	t = fu						106,489	0.97 (0.02)	0.12	0.98 (0.01)	0.082	7303	0.98 (0.02)	0.40	0.99 (0.01)	0.135
Attitudes (1– 5)	t = base	111,298	0.87 (0.02)	<0.001^f	0.95 (0.01)	0.016	104,152	0.98 (0.04)	0.54	0.99 (0.01)	0.079	7146	0.99 (0.05)	0.87	0.997 (0.02)	0.140
Attitudes (1– 5)	t = fu						105,353	1.009 (0.04)	0.80	1.004 (0.01)	0.080	7241	1.21 (0.06)	<0.001^f	1.08 (0.02)	0.129
Self-efficacy (Emotional; 1–6)	t = base	113,720	0.91 (0.01)	<0.001^f	0.95 (0.008)	0.016	106,438	0.97 (0.02)	0.28	0.99 (0.01)	0.082	7282	1.10 (0.04)	0.003	1.05 (0.02)	0.137
Self-efficacy (Emotional; 1–6)	t = fu						105,675	0.99 (0.02)	0.76	0.997 (0.01)	0.080	7229	1.19 (0.03)	<0.001^f	1.09 (0.02)	0.131
Self-efficacy (Friends; 1– 6)	t = base	114,078	0.91 (0.01)	<0.001^f	0.96 (0.007)	0.016	106,765	0.98 (0.02)	0.54	0.99 (0.01)	0.082	7313	1.11 (0.04)	0.003	1.05 (0.02)	0.136
Self-efficacy (Friends; 1– 6)	t = fu						106,156	0.98 (0.03)	0.46	0.99 (0.01)	0.081	7262	1.17 (0.04)	<0.001^f	1.08 (0.02)	0.131
Self-efficacy (Opportunity; 1–6)	t = base	113,900	0.90 (0.02)	<0.001^f	0.95 (0.01)	0.016	106,600	0.97 (0.03)	0.32	0.98 (0.02)	0.082	7300	1.18 (0.05)	<0.001^f	1.09 (0.02)	0.136
Self-efficacy (Opportunity; 1–6)	t = fu						106,512	0.997 (0.03)	0.91	0.999 (0.01)	0.081	7290	1.17 (0.04)	<0.001^f	1.08 (0.02)	0.129
Perceived physical risks (0–100%)	t = base	112,428	0.995 (0.0007)	<0.001^f	0.95 (0.007)	0.017	105,222	0.997 (0.001)	0.008	0.97 (0.01)	0.082	7206	1.003 (0.001)	0.02	1.03 (0.01)	0.132
Perceived physical risks (0–100%)	t = fu						105,979	1.0002 (0.001)	0.86	1.002 (0.01)	0.082	7285	1.002 (0.001)	0.11	1.02 (0.01)	0.134
Perceived social risks (0–100%)	t = base	113,404	0.997 (0.0006)	<0.001^f	0.97 (0.006)	0.016	106,128	0.999 (0.0009)	0.19	0.99 (0.009)	0.082	7276	1.004 (0.001)	0.001	1.04 (0.01)	0.133
Perceived social risks (0–100%)	t = fu						106,492	1.0003 (0.001)	0.72	1.003 (0.01)	0.081	7304	1.005 (0.001)	<0.001^f	1.05 (0.01)	0.133
Perceived addiction risks (0–100%)	t = base	109,822	0.999 (0.0006)	0.06	0.99 (0.006)	0.016	102,800	0.998 (0.001)	0.12	0.98 (0.01)	0.079	7022	1.002 (0.001)	0.23	1.02 (0.01)	0.137
Perceived addiction risks (0–100%)	t = fu						96,488	1.00005 (0.001)	0.97	1.0005 (0.01)	0.080	6666	0.999 (0.001)	0.51	0.99 (0.01)	0.134
Perceived benefits (0–100%)	t = base	104,778	0.998 (0.0007)	0.02	0.98 (0.007)	0.017	98,117	0.997 (0.001)	0.02	0.97 (0.01)	0.083	6661	1.002 (0.002)	0.14	1.02 (0.02)	0.128
Perceived benefits (0–100%)	t = fu						101,366	0.999 (0.001)	0.32	0.99 (0.01)	0.080	6982	1.0006 (0.001)	0.69	1.006 (0.01)	0.135
PBC (easy to quit; 1–5)	t = base	113,238	0.97 (0.01)	0.003	0.99 (0.004)	0.017	105,978	0.97 (0.02)	0.10	0.99 (0.007)	0.082	7260	1.01 (0.02)	0.54	1.01 (0.009)	0.138
PBC (easy to quit; 1–5)	t = fu						106,289	0.99 (0.02)	0.41	0.99 (0.007)	0.080	7271	1.04 (0.02)	0.06	1.02 (0.009)	0.136
PBC (to avoid smoking; 1– 5)	t = base	113,998	0.98 (0.01)	0.11	0.99 (0.004)	0.017	106,687	1.003 (0.02)	0.87	1.001 (0.007)	0.082	7311	1.04 (0.02)	0.08	1.02 (0.009)	0.137
PBC (to avoid smoking; 1– 5)	t = fu						106,084	1.01 (0.02)	0.48	1.005 (0.007)	0.080	7268	1.05 (0.03)	0.03	1.02 (0.01)	0.133
Objectively measured smoking behavior (0– 30)	t = base	104,680	0.93 (0.01)	<0.001^f	0.87 (0.02)	0.015	97,935	0.94 (0.02)	0.001	0.90 (0.03)	0.080	6745	1.02 (0.02)	0.39	1.03 (0.04)	0.135
Objectively measured smoking behavior (0– 30)	t = fu						104,927	0.97 (0.02)	0.16	0.95 (0.03)	0.083	7231	1.10 (0.03)	<0.001	1.19 (0.06)	0.135
Smoking susceptibility (binary)^e	t = base	113,856	1.20 (0.03)	<0.001^f	–	0.017	106,569	1.16 (0.05)	0.001	–	0.082	7287	0.93 (0.05)	0.17	–	0.138
Smoking susceptibility (binary)^e	t = fu						106791	1.26 (0.06)	<0.001^f	–	0.081	7311	0.96 (0.05)	0.46	–	0.138

^aResults are odds ratios, standard errors, and p-values from mixed-effects logistic regressions. In each model, the outcome variable is a binary variable representing whether the focal participant had: (1) nominated an individual from the school year group as a friend at baseline [0 = no friend nomination; 1 = friend nomination]; (2) added a potential friend from the school year group between baseline and follow-up [0 = potential friend not added; 1 = potential friend added]; or (3) dropped a friend from the school year group between baseline and follow-up [0 = baseline friend not dropped; 1 = baseline friend dropped]. The predictor variable is the absolute difference (on the original scale) between the focal participant and the individual on the smoking-related outcome variable at baseline (t = base) or follow-up (t = fu). Odds ratios represent the multiplicative change in odds of nominating/adding/dropping friends for a one-unit increase in the absolute difference between the focal participant and the individual on the smoking-related outcome variable (original scale) at baseline (t = base) or follow-up (t = fu). Random intercepts were included at the individual participant level, with cluster-robust standard errors. Analyses are based on participants providing network data at the two timepoints. OR: odds ratio; SE: standard error; ICC: intraclass correlation coefficient; PBC: perceived behavioral control.
^bFor comparability between predictor variables measured on different scales, the mixed-effects logistic regressions were repeated with the smoking-related outcome measures re-scaled to run between 0 and 10. Odds ratios represent the multiplicative change in odds of nominating/adding/dropping friends with a one-unit increase in the absolute difference between the focal participant and the individual on the smoking-related outcome variable (re-scaled) at baseline (t = base) or follow-up (t = fu). Random intercepts were included at the individual participant level, with cluster-robust standard errors. p-values remain the same as those extracted from the original model.
^cIntraclass correlation coefficients (ICCs) are defined as the ratio of the between-cluster variance to the total between-cluster and within-cluster variance (Killip et al., 2004).
^dHigher numerical values represent higher self-report anti-smoking outcomes, apart from objectively measured smoking behavior (higher numerical values represent higher levels of smoking behavior).
^eThe predictor variable is a binary variable representing whether the focal participant had the same smoking susceptibility status (0 = not susceptible to commencing smoking; 1 = susceptible to commencing smoking) as the individual at baseline (t = base) or follow-up (t = fu). Odds ratios represent the multiplicative change in odds of nominating/adding/dropping friends for matching susceptibility statuses compared to non-matching susceptibility statuses at baseline (t = base) or follow-up (t = fu). Random intercepts were included at the individual participant level, with cluster-robust standard errors.
^fRetained statistical significance at the 5% level after using the Holm–Bonferroni procedure to correct the p-values for multiple testing (p ≤ 0.05; based on all tests reported in Table 4).
Bold values show the results meeting the significance level of p ≤ 0.01.

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Table 4 Results of mixed-effects logistic regressions investigating selection homophily effects: (1) for friendship nominations at baseline; (2) for adding friends between baseline and follow-up; or (3) for dropping friends between baseline and follow-up.

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