Fig 1.
Network neighbourhood example.
The focal node in the centre (square) is related to all the other nodes (shown in light lines), who may be connected to each other (shown in dark lines). The neighbourhood can be divided into communities (shown in shades of green). Filled nodes have donated, and the focal node is surrounded by four donors, who are in three different communities, with a maximum of two nodes from the same community. The central question is whether contagion of donation is driven by cohesive reinforcement—in which case the common community donor degree should have a large effect—or by independent reinforcement—in which case the donor communities should have a large effect.
Fig 2.
Daily donor dynamics (a) are affected by FEC deadlines (raw data is transparent, smoothed data solid). The cumulative number of donors (b) shows the overall growth.
Fig 3.
The probability to donate based on (a) donor degree, (b) common community donor degree, (c) donor communities, (d) source diversity and (e) previous donation.
Fig 4.
Conditional donation probability.
Donation conditional on previous donation differs for (a, c) donor degree and (b, d) donor communities, with the effects for new donors being larger.
Fig 5.
Magnitude of (a) general effects, (b) network effects for new donors, and (c) network effects for old donors. Error bars show 95% confidence intervals for the coefficients.
Fig 6.
Cross-cutting donation probability.
Cross-cutting donation probability by (a) degree and (b) communities shows that exposure to one side can increase donations to the other side.
Fig 7.
Logistic regression results for cross-cutting effects.
Effect sizes for cross-cutting exposure distinguished by old/new donors for (a)–(b) donor degree, (c)–(d) common community donor degree, (e)–(f) donor communities, and (g)–(h) source diversity. Error bars show 95% confidence intervals for the coefficients.
Fig 8.
Predicting total campaign contributions.
We predict the total amount donated throughout the campaign based on donations in the first quarter only. Line shows average and the shade shows the 5% and 95% percentiles.