How is a precision study typically performed?

• A. By scanning 10 people twice
• B. By scanning 30 people twice or 15 people three times with repositioning
• C. By scanning the same person multiple times on the same day
• D. By scanning 100 people once

Answer: (B)

A precision study is conducted to assess the consistency of measurements produced by a specific bone densitometry device. The goal is to determine how reliably the equipment can produce similar results under the same conditions.

Scanning 30 people twice or 15 people three times with repositioning allows for a thorough evaluation of the device's performance. This method accounts for variations in positioning and technique, which can impact bone density measurements. By including a sufficiently sized sample and multiple scans, the data collected can demonstrate variability, helping establish the precision of the equipment. This approach reflects real-world conditions where precise measurements are crucial for accurate diagnosis and treatment planning.

Using a smaller sample size or fewer repetitions could lead to inconclusive results about the equipment's precision, as it may not adequately capture the potential variability arising from patient movement or differences in technician technique. Consequently, the chosen method for the precision study emphasizes reliability and reproducibility, which are vital factors in clinical settings where bone health assessments are performed.