Table 1. Treatment effect calculations for encouragement and lottery email treatments.

Comparison groups		ITT
No email	Encouragement email
.1591(N = 15,123)	.1797 (N = 3,778)	.0207 (p = .002)
No email	Lottery email
.1591 (N = 15,123)	.2191 (N = 3,779)	.0601 (p<.001)
Encouragement email	Lottery email
.1797 (N = 3,778)	.2191 (N = 3,779)	.0394 (p<.001)
Among those opening email		ATT
Encouragement email	Lottery email
.2030 (N = 2,729)	.2677 (N = 2,585)	.0647 p<.001)

ITT p-values based on a difference of proportions test using intent-to-treat calculations. ATT p-value based on a difference of proportions test among those opening the treatment emails.