In this presentation the difference between individual risk factors & risk factors in populations was discussed. In psychiatry, the two may interact, e.g. the effect of unemployment may depend on the local level of unemployment. The work of Neeleman provides empirical evidence to support these theoretical constructs in suicide & deliberate self-harm. Examining suicide within the 103 electoral wards of South London, he showed the suicide rate for a member of an ethnic minority varied accordingly to the density of that minority. Social factors operate according to the prevalence of that factor – what is a risk factor in one area can be protective in another.