Comment on 'Estimating average annual per cent change in trend analysis' by Clegg LX, Hankey BF, Tiwari R, Feuer EJ, Edwards BK, Statistics in Medicine 2009; 28:3670-3682
Stat Med. 2010 Aug 15;29(18):1958-60; author reply 1961.
doi: 10.1002/sim.3850.
We discuss some issues relevant to paper of Clegg and co-authors published in Statistics in Medicine; 28, 3670-3682. Emphasis is on computation of the variance of the sum of products of two estimates, slopes and breakpoints.