No doesn't always mean no

Just because someone decides not to participate in a research project doesn't necessarily mean that they fundamentally object to taking part, a study published online in BMC Health Services Research suggests.

Misunderstandings about the nature and process of a study often contribute to expressions of non-consent, a factor that should be incorporated in the design of future studies.

Low participation rates are a problem in human subject research because they can lead to delays, sampling bias and increased costs. Most studies to date have focussed on participants' motives for participation, so Brian Williams and colleagues from the University of Dundee, UK, decided to study the reasons why people chose not to take part in research projects.

They studied a group of older people living in Scotland who had opted out of a survey about retirement activities. Around half of the initial 887 people invited to participate declined to do so. Approximately 60% of these then agreed to take part in Williams' follow-up study and give reasons for their original refusal. Most were willing to take part, but had refused to do so because of confusion about the nature and purpose of the research, and perceived difficulties in participating because of other commitments. Only 28% indicated they were "not interested in research."

The results query the meaningfulness of expressions of 'non-consent' - a term that can encompass a variety of hidden personal decisions and motives. Reasons for non-participation are highly specific, not just to the research topic, but also to the potential participants. The information sheets that accompany participation requests should therefore aim to clarify any potential sources of confusion, and behavioural theory could be used to aid study design.