Probability of changing ego’s screen time in the next time step, based on ego’s and average alters’ current screen time score (in 10 hour intervals).

<p>Change means increasing or decreasing by one 10 hour interval, or staying at the same level.</p

Probability of changing ego’s playing active sports score in the next time step, based on ego’s and average alters’ current active sports score.

<p>The playing active sports score is the frequency in the past week: 0 = not at all; 1 = 1 or 2 times; 2 = 3 or 4 times; 3 = 5 or more times. Egos may increase by one level, decrease by one level, or stay at the same level.</p

Network influence on behavior, parameters and (95% confidence intervals).

<p>Behavioral change parameters are adjusted for network structural parameters (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039795#pone-0039795-t003" target="_blank">Table 3</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039795#pone-0039795-t004" target="_blank">4</a>).</p><p>Linear and quadratic shape parameters are the effects of the ego’s own behavior (linear) and behavior-squared (quadratic) on his or her future behavior. The “average similarity” parameters represent social influence of the alters’ on the ego.</p

Structural influences on network for Jefferson and Sunshine High, parameters and (95% confidence intervals).¹

1<p>Parameters are the weights actors place on various network configurations. They are the contributions to the objective function. The 95% confidence intervals quantify the precision of the estimates a score function method.</p>2<p>The basic rate parameter for friendship controls how often actors have the opportunity to change their network (add, keep, or drop a friend). Higher values indicate more network changes.</p>3<p>The outdegree parameter is the weight placed on having a friendship tie with <i>any</i> member of the social network, irrespective of the alter’s characteristics.</p>4<p>The reciprocity parameter is the weight an actor places on reciprocating alters’ friendship nominations.</p>5<p>The transitive triplets parameter is the weight an actor places on naming friends who are also named by the actor’s friend.</p>6<p>Positive values of “same” and “similarity” measures are the effects of homophily on these attributes.</p

Respondent characteristics at baseline (Wave 1), unless otherwise noted.

<p>For continuous measures, mean values are given with standard deviations in parentheses. For categorical variables, percentages are given.</p>1<p>“Sum of BMI similarities” is the mean value for the <i>total sum of</i> BMI similarities between the actor and each of his or her alters.</p>2<p>“BMI average similarity” is the mean value for the <i>average</i> similarity between an actor and his or her alters.</p

Behavioral influence on network choice for Jefferson and Sunshine High, parameters and (95% confidence intervals).

<p>Network change parameters are adjusted for structural (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039795#pone-0039795-t003" target="_blank">Table 3</a>) and behavior change parameters (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0039795#pone-0039795-t005" target="_blank">Table 5</a>).</p>1<p>Positive values for attractiveness indicate that egos generally prefer to become or maintain friendships with alters who have high levels of the BMI or behavior; negative values indicate a disinclination to keep or maintain friendships with individuals with high levels of the BMI or behavior.</p>2<p>Sociability indicates that egos with high levels of BMI or the behavior prefer to have more friends.</p>3<p>Similarity is the measure of homophily on BMI or the behavior. Positive values indicate a preference for alters whose values are similar to the ego’s.</p

Key terms used in this paper.

<p>Key terms used in this paper.</p

Probability of ego’s increasing (+1), decreasing (−1), or remaining at the same body mass index (BMI) in the next time step, based on ego’s and average alters’ current BMI.

<p>Probability of ego’s increasing (+1), decreasing (−1), or remaining at the same body mass index (BMI) in the next time step, based on ego’s and average alters’ current BMI.</p