Correction to: Journal of Exposure Science and Environmental Epidemiology (2006) 16: 30–38; advanced online publication, July 6, 2005; doi:10.1038/sj.jea.7500434

On page 3 of the Methods section, the equation is incorrect.

The correct equation is shown here:

The subject-specific slope of Xt is [β1(θ1+φi)]. However, the fixed-effect (or average) slope of Xt is still β1θ1, which is the quantity of interest as described in the article.

The authors would like to apologise for this mistake.