Table 3

Change in variance in practices' quality scores 1998-2003

Pitman's t test of correlated variances
ConditionSD; range in 1998SD; range in 2003tdfP value
Coronary heart disease (41 practices)9.68; 37.36-75.6711.10; 44.8-94.80.84390.41
Asthma (42 practices)16.47; 20.6-85.515.93; 35.8-96.6–0.23400.82
Diabetes (42 practices)13.74; 35.0-88.911.44; 43.2-93.4–1.34400.19