Table 1. Result of linear regression of the student’s academic progress over one year (y) on four independent variables measured in January 2011.

	DF	SS	MS	F-statistic	p-value
g	1	9011.83	9011.83	12.7903	0.000467***
x acquaintance	1	1877.14	1877.14	2.6642	0.104686
x friend	1	4481.44	4481.44	6.3604	0.012692*
x best friend	1	2785.15	2785.15	3.9529	0.048574*
Error	153	107801.	704.58
Total	157	125956.

y  =  −14.124 + 0.204g + 0.127x _acquaintance + 0.230x _friend + 0.147x _{best friend}

Independent variables are: g: student’s academic ranking, and x _i: difference in ranking between each student’s self-reported neighbors’ average GPA and his/her own GPA, where i is either acquaintance, friend or best friend. A highly significant effect of g was due to the fact that top-ranked students did not change their academic rankings much after one year.