Physical and mental health are measured on the basis of the 'Short Format 12' or 'SF-12' in Statistics Netherlands’ Permanent Life Situation Survey (POLS). Older people whose scores for physical or mental health are in the lowest 10 percent are defined as being in poor physical or mental health respectively.
The annual sample size of people aged 50 to 80 years in POLS is around three thousand. In this analysis, survey years 2004, 2005 and 2006 are combined. Residents in homes and institutions are excluded form the survey. As the figures are based on a sample survey, they are subject to a margin of error.