Calculating Townsend scores: An introduction

Amy Bonsall one of our interns talks about what deprivation is and how it could be calculated.

As a student at the University of Manchester studying criminology I was lucky enough to get the opportunity to work on a project with the UK Data Service as an intern calculating Townsend Deprivation Scores for the UK and importantly, learning work environment skills that will be useful once I graduate. My fellow intern (Sanah) and I came with a thirst to learn and an ambition to make the project a success which has made the exciting aspects more rewarding and the obstacles we need to come much more bearable.

Deprivation is a lack of reasonable provisions. This could be in a social way or material. Because there are so many indicators of deprivation and it cannot be measured in one objective way as it is a construct so many deprivation indices have been developed. Each of these indices have their benefits for measuring deprivation as well as areas where they are lacking.

Different methods of calculating have been developed due to a long term need to research deprivation through census data and the ever-changing indications of deprivation. I am currently using the 2011 census to calculate deprivation scores for the UK using the Townsend index. This is just one of many ways deprivation can be calculated however, we have decided this one is appropriate as it measures material deprivation exclusively rather than incorporating social deprivation meaning it can be consistently calculated over time. It is also comparable across the UK.

Before jumping into the data and calculating the deprivation scores it was important to first understand what Townsend’s Index measures and how to measure it. Information on the index was readily available and easy to find giving the initial feeling that the resources required at each stage of the project would be easily found (they weren’t).

Research taught us that Townsend Deprivation scores are calculated based on 4 indicators of deprivation: non-home ownership, non-car ownership, unemployment and overcrowding.

This is calculated by first finding percentage non-car ownership, percentage non- home ownership, percentage unemployment and percentage overcrowding.
The percentages for each area then need to be normalised for the unemployment and overcrowding indicators as these results are very skewed this is done by: ln(percentage value +1).

Z scores are then calculated using the percentage values for each ward under each indicator. For the unemployment and overcrowding variables, the logged versions are used instead.
Z scores= (percentage – mean of all percentages)/ SD of all percentages
Z scores of logged variables= (log percentage – mean of log percentages)/ SD of log percentages

Total of the 4 Z scores= Townsend Deprivation Score


Through the sources found it wasn’t perfectly clear how to calculate Z scores from the logged variables. There was no clarification about whether to take the mean and standard deviation of the percentages after they are logged or before. Taking information from different sources gave a good idea of the correct formula, however, the important next step is to test this formula against existing scores to ensure it is correct before continuing the process of this project.

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