Table 4

Process evaluation measures

MeasureExample questions to be answeredMethod
ContextWhat type of phone/platform did participants use, for example, Android, iOS?
How did participants/helpers access the website for example, on phone, on desktop, on tablet?
Were there any differences between social networks and what impact did these have on outcomes?
Quantitative analysis
Social Network Analysis
Qualitative interviews with participants and helpers
FidelityWas the intervention delivered as intended?
When, if any, were any adaptations needed to the planned intervention?
Descriptive analysis of data usage statistics from software company
Qualitative interviews with participants and helpers, and study team
ExposureHow often did participants/helpers use the app and website?
How often did participants/helpers access the goal setting/monitoring feature of the app and website?
How often did participants/helpers interact with each other via the app and website?
What were the patterns and trends of usage over time?
Analysis of data usage statistics from software company
ReachHow well does the study sample represent the population of interest?
To what extent did the intervention reach and influence people other than recruited participants, including helpers?
What were the particular difficulties/issues that arose during the study in delivering the intervention?
Descriptive statistics
Qualitative interviews with participants and helpers
Recruitment and retentionWhat are the difficulties in recruitment?
What is the attrition rate overall and by group?
What venues do participants chose to meet for their fieldworker appointments?
What are the reasons for withdrawal?
What factors were involved in ongoing engagement with the intervention?
Quantitative analysis
Qualitative interviews with participants and helpers
ContaminationWhat are the characteristics of other groups’ people are attending, for example, slimmer’s groups?
Have any of the control group seen intervention content from other participants or acted as a nominated helper?
Quantitative analysis
Qualitative interviews with participants and helpers
Control armWhat is happening in the control arm?Qualitative interviews with participants
Mechanisms of impactWhat role does social network play in how participants use the intervention?
How did participants perceive their social support for healthy eating and physical activity changed throughout the intervention?
Mediators of change questionnaires (see table 3)