For the pre-implementation, the aggregated point estimate for the percentage return rate for those who booked was 61.47 (95% CI = 61.20, 61.74; n = 75,414/122,681) and for those who did not book, 21.49 (95% CI = 21.28, 21.70; n = 31,738/147,672). For the post-implementation, the aggregated point estimate for the percentage return rate for those who booked was 62.35 (95% CI = 61.96, 62.74; n = 36,472/58,500) and for those who did not book, 30.55 (95% CI = 30.28, 30.82; n = 34,156/111,817). For those who had booked, there was a 0.88% (95% CI 0.402, 1.358) significant ( Z = 3.610, P = 0.0003) increase in returning donors. For those who had not booked there was a 9.06% (95% CI = 8.718, 9.402) significant ( Z = 51.963, P < 0.001) increase in returning donors. There was a significant interaction with the percentage increase in return rates for those who had not booked, significantly greater than those who had booked ( Z = 27.292, P < 0.001), with a percentage difference of 8.18% (95% CI = 7.593, 8.767). Analyses were conducted using procedures for Z tests for proportions detailed in refs. 98 , 99 and implemented in ZumaStat 4.0. All analyses were two-tailed and no adjustments were made for multiple comparisons. Error bars are 95% CIs.
