RT Journal Article SR Electronic T1 The reliability and validity of the age-sex register as a population denominator in general practice JF The Journal of the Royal College of General Practitioners JO J R Coll Gen Pract FD British Journal of General Practice SP 283 OP 286 VO 28 IS 190 A1 Fraser, Robin C. YR 1978 UL http://bjgp.org/content/28/190/283.abstract AB I report evidence which raises doubts about the reliability and validity of age-sex registers as true population denominators in general practice in the UK. These have potentially disturbing implications for the interpretation of data based on the presumed precision of age-sex registers. I am undertaking a prospective study to identify and quantify sources of inaccuracy to try to establish a method of estimating the true population at risk and its true age-sex characteristics. This would greatly enhance the utility of the age-sex register as the most valuable tool in general-practice research.