Medical Device Measurement Accuracy: The Good, The Bad And The Ugly
By Jim Tennerman, North American Life Science segment manager, Vaisala Oyj
Measurement accuracy is a subjective concept applied to all kinds of measurements. Generally speaking, accuracy refers to the degree of “closeness” of the measurement to a “true value.” This definition is usually good enough, but not always. The subjective nature of accuracy allows for a wide variety of claims that may technically be true, but misleading at the same time.
Let’s consider this in the context of measuring relative humidity (RH). RH is expressed as a percentage, so the possible range of RH is 0 to 100%. Manufacturers of RH measurement equipment typically specify accuracy as a ± value of some percent. For example, one might say that a certain device is accurate to ± 3% RH. Due to the competitive nature of the instrumentation manufacturing business, makers of a different device may claim to be more accurate with ± 2% RH. Superficially, with all other things being equal, this ±2% device would appear to be “better.” Beware, because this is not always the case and can be misleading until you dig deeper. In this article we’ll look at how you start digging.