Table 1.

Categorisation of all screened articles into sub-fields and article type

Research fields and sub-fields	Article type
	Incentives	Strategies	Opinion Pieces	Observational Studies	Total: field of studies
Health and Medical Research
Psychology	1	2	4	1	8
Genetics	0	16	12	17	45
Other	0	58	69	88	215
Total: health and medical research	1	76	85	106	268
Non-Health and Medical Research
Astronomy	0	0	0	1	1
Ecology	0	5	11	8	24
Information Technology	0	38	26	28	92
Other	0	46	52	87	185
Total: non-health and medical research	0	89	89	124	302
Total: type of studies	1	149	174	230	570