REMINDER
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The next seminar of the South Wales local group of the RSS is on Wednesday 16th November at 5:00pm (4:30pm for tea) at the Cinema, Welsh Assembly Building, Cathays Park, Cardiff.
Linear regression with errors in both variables; a problem solved.
J. W. Gillard, T. C. Iles (Cardiff University)
Abstract
Many experimental procedures involve fitting a straight line to a set of bivariate data (x,y). Standard linear regression could fit this line, but it assumes that measurement error is only associated with one variable - x or y. In many situations, the scatter about the true line will be caused by measurement error in both variables. Here, standard linear regression estimators for the line are biased and should be avoided.
This talk will consider how to fit a linear regression when there are errors in both variables. This is commonly known as errors in variables modelling. An example using AFP data (used to detect Down's syndrome) will motivate the talk. A maximum likelihood approach will be briefly outlined, but an alternative approach using the method of moments will take centre stage. This alternative approach has a number of distinct advantages, all of which will be outlined during the talk. Details will be given during the talk of a method of approach in fitting lines where both variables are subject to measurement error. These guidelines have been specifically devised for practitioners.
The seminar will be preceded by an AGM.
Rebecca Cannings-John
Statistician
Cardiff University
Department of General Practice
Room 2F 15
Cardigan House
Wales College of Medicine
Heath Park
Cardiff
CF14 4XN
Tel: 029 2074 5105
www.uwcm.ac.uk/study/medicine/general_practice
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