Detailed Explanation:

The best area for focused quality improvement is determined by comparing the hospital’s infection rate to the state mean infection rate and the confidence interval:

Analysis of Each Procedure

Total Hip Replacement: Hospital infection rate is lower than the state mean (0.4% vs. 0.9%), suggesting a lower risk than average.

Total Knee Replacement: Infection rate is slightly above the state mean (1.1% vs. 1.0%), butwithin a narrow confidence interval (0.8%-1.2%).

ACL Reconstruction: Infection rate aligns with the state mean (1.5%) and has a narrow confidence interval (1.4%-1.6%), indicating less room for reduction.

Total Shoulder Replacement: Hospital rate (1.3%) is higher than the state mean (0.9%), with a broader confidence interval (1.0%-1.6%), suggesting potential variability and room for improvement.

Conclusion

Total Shoulder Replacement (D) has the greatest opportunity for improvement, as its infection rate is notably higher than the state mean, and the confidence interval suggests variability in infection rates.