A single-blind randomised controlled trial of the effects of a web-based decision aid on self-testing for cholesterol and diabetes. study protocol

Table 2 Outcome measures and timing of data collection

Construct	Measures	No. of items	Questionnaire*
Primary outcomes
Knowledge	Knowledge questionnaire based on information provided in the decision aid	20 Statements (True/false/don't know)	2
Secondary outcomes
Attitude	Marteau [26]	4	1,2
Ambivalence	Felt ambivalence [24]	3	1,2
Follow-up behaviour	Uptake of self-tests, visiting a doctor, changing lifestyle.	7	3
Intention	Intention towards self-testing, seeing a doctor.	2	1,2,3
	Intention towards changing lifestyle	1	2,3
	Stages of change [27]	1	1,2,3
Psychosocial determinants	Perceived benefits and barriers	14	2
	Self-efficacy	3	2
	Response-efficacy	4	2
	Perceived susceptibility/risk perception [28]	3	1,2,3
	Cues to action	1	2
	Perceived severity	1	2
	Anticipated regret	1	2
	Moral obligation	2	2
	Subjective norm	1	2

*Questionnaire 1: baseline. Questionnaire 2: directly after seeing intervention or control condition. Questionnaire 3: three months after viewing intervention or control condition

ISSN: 1471-2458