Table 2.

Number and frequency of codes in each coding iteration (coding rounds R1 and R2).

	Main Codes	R1/R1 f Total	R1: REC	R2	R2: REC	R2 f Total
	Recommendation (REC)	84	100	45	56	103
	App	50	35	27	20	53
	Barriers for further action	43	3	15	3	45
	Possibilities (if improved)	37		21		45
	Hardware	24	17	16	9	27
	Motivation	22		14		25
	Positivity about the general idea	18		8		21
	Data loss	14	3	5	1	18
	Web visualization	13	5	9	2	16
	General user experience	13		9		13
	Expectations	7		4		8
	Privacy	7	2	2	1	7
	Quitting (reasons)	6		4		7
	Battery	7	5	2	4	7
	Length of use	4		4		6
	Data connection	6	5	2	3	6
	App visualization	3	2	4	2	4
	Data quality	4	1	4	1	4
	GPS	4	6	3	4	4
	Optimal participation time	4	3	1	1	3
	Product price	2	2	3	1	3
	Behaviour	3		1
	Time	10		2
	Data visualization		8		4
	External people	2		3
	LEO	26	3	4
	CityAir	25		5
	Uncategorized	5		6
Total	28	443	100	202	56	425

¹ Under “Possibilities” in R2; ² Mostly covered by “Barriers for further action” in R2; ³ under “Possibilities” in R2; ⁴ covered by other categories in R2; ⁵ Excluded as it is outside the scope of this paper, pertaining to another data collection tool used in CITI-SENSE; ⁶ categorized in R2.