Table 1.

Characteristics and Representativeness of Practice Sample (n = 42) Compared With All General Practices in England

CharacteristicNaMeanSD10th PercentileMedian90th Percentile
GMS = General Medical Services; IMD = Index of Multiple Deprivation; NHS = National Health Service; QOF = Quality and Outcomes Framework: SOA = Super Output Area.
a Practice list sizes from GMS data (Reused with the permission of The Health and Social Care Information Centre).
b QOF achievement obtained from the NHS Information Centre (
c Data correspond to all practices in England.
d IMD data available from the Communities and Neighbourhoods Web site (
Overall QOFb achievement 2007
    Study sample4289.63.586.190.093.1
Practice list size 2007
    Study sample426,6203,8462,3706,11811,342
Overall QOF achievement 2005
    Study sample4280.
Practice list size 2005
    Study sample416,6173,8372,4565,92111,481
Practice list size 2003
    Study sample396,3673,7672,1635,86211,270
Deprivation: SOA IMDd (2005)
    Study sample4227.320.67.320.162.7