Table 3.

Coefficients [s.e.] for the linear models tested for percentage weight change. Every row corresponds to a model for weight change of individuals with an engagement time of 120 days and at least one friend, after correcting for self-selection bias. The total number of observations is 22 419 (1104 uncensored), except for models that include as variable the average weight change of a user's friends (1076 uncensored observations). We denote as uncensored observations those for whom we have the values of all variables, and as censored observations those for whom we are missing the values of some variables. Superscript n.s. denotes not significant.

intercept	initial BMI	number of weigh-ins	time in the system	online communic.	k-shell index	number of friends	betweenness	avg. weight change friends	inv. Mills ratio	adj. R2 (%)
−2.02n.s. [1.31]	−0.11*** [0.02]	−0.09*** [0.01]	−0.007*** [0.001]						1.87*** [0.40]	17.8
0.10n.s. [1.41]	−0.11*** [0.02]	−0.09*** [0.01]	−0.006*** [0.001]	−0.004*** [0.001]					0.86n.s. [0.48]	18.7
0.04n.s. [1.34]	−0.10*** [0.02]	−0.09*** [0.01]	−0.006*** [0.001]		−0.31*** [0.06]				0.92* [0.43]	19.7
−2.01n.s. [1.31]	−0.10*** [0.02]	−0.09*** [0.01]	−0.007*** [0.001]			−0.008n.s. [0.005]			1.82*** [0.40]	17.9
−2.04n.s. [1.31]	−0.10*** [0.02]	−0.09*** [0.01]	−0.007*** [0.001]				−6.03n.s. [11.91]		1.87*** [0.40]	17.7
−1.54n.s. [1.27]	−0.08*** [0.02]	−0.10*** [0.01]	−0.007*** [0.001]					0.03** [0.01]	1.61*** [0.38]	18.8
1.55n.s. [1.36]	−0.08*** [0.02]	−0.09*** [0.01]	−0.006*** [0.001]	−0.003* [0.001]	−0.27*** [0.06]			0.03* [0.01]	0.10n.s. [0.46]	21.4

***p < 0.001.

**p < 0.01.

*p < 0.05.