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Table 1 Comparison of the numbers of hospitals achieving NSF goals and the number inside and outside 3 sigma limits.

From: Funnel plots, performance variation and the Myocardial Infarction National Audit Project 2003–2004

  DTN CTN Aspirin Beta-blocker Statin
Analysis by attainment of NSF targets
Reaching the goal 163 102 191 151 180
Within 25% of the goal 51 0 16 46 24
More than 25% from the goal 8 116 0 3 2
Less than 20 cases 8 12 20 25 20
Total 230 230 227 225 226
Analysis by funnel plot
Above UCL 33 32 40 43 34
Within limits 182 170 187 152 164
Below LCL 15 28* 24 30 31
Total 230 230 227 225 226
Discrepancy between table and funnel plot assessment of performance
Within target and below LCL 0 0 8 0 5
Within 25% of target but below LCL 8 28* 16 27 24
Beyond 25% of target and below LCL 7 0 0 3 2
Within target but above UCL 27 32 37 44 35
Total discrepancy 42 60 61 74 66
  1. DTN = door to needle time, CTN = call to needle time, Statin = HMG-CoA reductase inhibitor, NSF = National Service Framework for Coronary Heart Disease.
  2. *The 'within 25% of target' did not apply to CTN 60. In total, 108 hospitals were above the 48% target and 122 below it, of which 28 were also below the LCL.