Comprehensive and Detailed Explanation From Exact Extract:

In the Health Data Analytics domain, control charts are used to assess process stability and variation over time.

The chart shows that the medication error rate initially fluctuated, reaching a peak above the mean, and then displayed a sharp and sustained decline below the lower control limit (LCL) during the last several months.

A drop beyond the LCL indicates a special cause variation, suggesting a significant change in the system — in this case, a substantial reduction in reported medication errors.

However, because the data only reflect the number of reported errors, not the actual rate of occurrence, it is more accurate to conclude there has been a reduction in reported errors — not necessarily that patient safety goals have been met.