Cartograms – The CASA Blog Network

London Population Change 2001 to 2009

Posted on Monday 23 January 2012 by chris

In a previous post I talked about the Index of Multiple Deprivation (IMD) in London, and how a “standard” representation only reflects the geographical reality of the land. By utilising a cartogram tool this potential issue can be overcome by rescaling each areal unit by its resident population, for the IMD I used mid-year population estimates available from the Office for National Statistics at Lower Layer Super Output Area (LSOA) level. To add a layer of context to the previous maps, I have constructed cartograms for London to illustrate the change in population between 2001 and 2009. I have used 2001 census data along with 2009 mid-year population estimates to calculate the percentage change for each of the 24,140 output areas (that contain on average 250 individuals nationally) that make up Greater London for the age ranges: 0-4, 5-14, 15-24, 25-44, 45-64 and 65 and over. To create the cartogram aspect of the maps I have used the total population of that particular age range in 2009 to rescale each areal unit. I have also produced the same population change maps using the “standard” representation of London to allow comparison with the cartograms. The results of this can be seen […]

2001, 2009, Cartograms, census, Change, london, Mid-Year Population Estimates, population, Research

London Index of Multiple Deprivation Cartograms

On my previous post I talked about the Index of Multiple Deprivation (IMD) in a London only setting. A common trait with the maps I created and those you can find elsewhere is the use of LSOA boundaries that reflect the geographical reality of the lay of the land. When concentrating on London in particular this does have an impact on how you perceive deprivation. This is in part down to how Lower Layer Super Output Areas (LSOAs) are constructed. An LSOA by design has to contain at least 1,000 residents and 400 households, with a national average of around 1,500 residents. London of course does not just consist of the denser populated core, but also more rural areas on the outskirts. As the methodology dictates that each LSOA has to have at least 1,000 people in it, the geographical extent of LSOAs tends to be larger in these more rural areas. This means visually they will be more dominant than central areas and can give a “false” impression as to how much of London’s population live in either more or less deprived areas. In an attempt to try and address this visualisation problem I have used the Cartogram Geoprocessing […]