Does two-year stability for scale scores of psychosocial factors differ by socioeconomic position?

Previous longitudinal studies have demonstrated the importance of measuring stability of risk factors over time to correct for attenuation bias. The present aim was to assess the stability of scores for eight psychometric scales over a 2-yr. period and whether stability differed by socioeconomic position. Baseline data were collected during 2003-2004 from 1,007 men and women ages 45 to 69 years. Follow-up data were collected in 2006 from a total of 795 men and women. Analysis showed that stability over 2 yr. was moderate and tended to be lower in groups of low socioeconomic position. It is suggested that correction of attenuation bias is relevant in longitudinal studies for psychosocial factors, especially for groups of low socioeconomic position.