Table 2.

Engagement with the recommender system among 731 users

	n or mean [std]	Percent, %
overall response rate (mean [SD])a	24% [34%]
levels of response rate
0	279	38.2
> 0 & ≤0.1	153	20.9
> 0.1 & ≤0.6	151	20.7
> 0.6 & ≤1	148	20.2
did not respond to the first message	428	58.6
did not respond to the last message	611	83.6
unsubscribed to receiving messages	113	15.5

^aThe response rate for each user is defined as the number of messages the user rated by the total number of messages the user received. On average, a user received 59 (SD = 16) messages and responded to 13 (SD = 20) messages. The overall response rate was calculated by averaging the response rates of the 731 users