How is Statistical Significance calculated?
We use significance tests to determine if a hospital’s quality or cost is statistically Above Average Quality or Below Average Quality. Each test is performed at the 0.05 significance level. This means that there is only a 5% chance that the size of the difference could have occurred by chance. Statistical Significance for Quality Stroke, Hip Fracture, and Hip Replacement Mortality Rate Data An individual hospital’s performance is measured by comparing the confidence interval (CI) for a hospital to the statewide mortality risk-adjusted rate (RAR). The hospital’s performance is described by whether its risk-adjusted mortality rate statistically is not significantly different, statistically is significantly higher, or statistically is significantly lower than Massachusetts’s risk-adjusted rate (using the 95% confidence interval). If a hospital’s CI intersects the statewide RAR, the hospital’s risk-adjusted mortality rate statistically is neither significantly higher or lower than the sta
