A Pharmacy and Therapeutics Committee has reviewed the following control chart for presentation to a...

The control chart shows a clear pattern of medication errors increasing above the upper control limit during the early months, indicating a period of instability or special cause variation. After this peak, there is a marked and consistent decline in error rates, falling well below the mean and approaching the lower control limit by the end of the year.

According to The Joint Commission and Institute for Healthcare Improvement (IHI) guidelines on control charts and statistical process control:

When data points fall outside control limits, this indicates special cause variation that warrants investigation.

The sustained decrease below the mean and toward the lower control limit strongly suggests a significant reduction in the medication error rate over time, which is statistically and clinically important.

Option A is premature; improving patient safety is multifactorial and while error rates decreased, meeting a strategic goal requires additional evidence of sustained improvement and outcome measures.

Option B accurately reflects the data trend showing a significant reduction in reported medication errors.

Option C is not supported; while errors increased in spring and summer, the chart does not specify the severity of errors, only the rate.

Option D is incorrect as there is no evidence that reporting of errors improved; instead, errors themselves declined.