Have you ever been on an international flight? The altimeter alternates between 8,839 and 9,144 meters. These readings correspond to 29,000 and 30,000 feet, respectively. There are 2 significant digits in the actual reading, so the altimeter should really read 8,800 meters and 9,100 meters–this is due to significant figures.

The error we see in both of the above examples is false precision. It is similar to the error that you have in your manual, only the conversion factors listed are wrong, too.

This should really be remedied. Sure, the clinical difference between 46.8 and 46.5 may not be all that significant–unless it is. Some treatment guidelines for cancer use tumor volume to guide changes in therapy. An error of a third of a cubic centimeter may not seem like a lot, but the cause of the error is an incorrect conversion factor.

This isn’t the first time errors like this have occurred. I’ll provide an everyday example. You are sick, and have a fever. What is the normal body temperature? Common wisdom says that the answer is 98.6°F, but actually that measurement comes from a classic German study that estimated a normal body temperature at 36.6°C. The German study had 3 significant figures. Converting the result of the study carried out in Germany–and accounting for significant figures–common wisdom would (correctly) be that a normal body temperature is 97.9°F. Unfortunately, whoever did the calculation originally rounded the data from the study carried out in Germany to 37°C, converted to Fahrenheit, and got our current (incorrect) result of 98.6°F (3 significant figures, converted from a measurement with only 2).

Even the normal human body temperature that everyone knows to be correct is wrong because calculation errors–like the ones present in the AMA Manual of Style– are ignored.