Challenges of harmonising data from UK national health surveys: a case study of attempts to estimate the UK prevalence of asthma. (November 2015) - Nwaru, Bright I; Mukherjee, Mome; Gupta, Ramyani P; Farr, Angela; Heaven, Martin; Stoddart, Andrew; Bandyopadhyay, Amrita; Fitzsimmons, Deborah; Shields, Michael; Phillips, Ceri; Chamberlain, George; Fischbacher, Colin; et al.