Table 2.

Sample characteristics

	SMS group
	Reason	Succinct	Opt out	Send failed	Total
Total n	138	135	95	7	375
Weartime data available	133	129	83	7	352
Female	28%	30%	27%	43%	30%
M age (SD)	17.9 (1.8)	18.2 (2.6)	18.9 (4.3)	18 (1.4)	18.3 (2.9)

Note: One person from both SMS groups missed the first message due to phone number imputation failure. This was considered to be of no practical consequence and they were counted as having received their intervention as planned