Evaluation of Placement Guidance Devices

• Activity Number: 66
• Type: Topic Contributed
• Date/Time: Sunday, July 31, 2011 : 4:00 PM to 5:50 PM
• Sponsor: Biopharmaceutical Section
• Author(s): Jeng Mah*+
• Keywords: diagnostic information ; operating characteristics ; decision parameter ; combined accuracy measurement ; comparison

Abstract

A placement guidance device is intended to measure the location of an object being placed and signal a hit when the object reaches a target zone. Accuracy of a placement device is gauged by the dual probabilities of true and false indications of the object's actual location. Evaluating this type of devices appears to be a two-class prediction problem similar to a standard disease diagnostic test, but with special conditions imposed by the placement process: since a false positive will erroneously end the placement process, the true positive and false negative readings can only occur following a true negative result. In addition, the probability of the device indicating any hit (true or false) is always of interest in the evaluation of such a device.

We examine operating characteristics of positive and negative outcomes under this model in response to the decision parameter. We also present work towards an optimal combined measurement for the evaluation and comparison of placement guidance systems.