Figure 1.

Pathways through which individuals may be filtered before becoming potential research respondents. Note: In systems such as in the UK, referral from secondary and tertiary services is almost always through primary care. This is not the case in all health care systems. N = true population. n = study

Zaccai et al. BMC Neurology 2006 6:2   doi:10.1186/1471-2377-6-2
Download authors' original image