A biologic control subject performs DLCO measurements on 20 consecutive days,and the following statistics are calculated: The coefficient of variation for the DLCO in this subject:
A) Is approximately 4.5%
B) Cannot be calculated until 30 measurements have been made
C) Suggests that the patient may have asthma
D) Indicates that the DLCO system displays excessive variability

Question

A biologic control subject performs DLCO measurements on 20 consecutive days,and the following statistics are calculated:  The coefficient of variation for the DLCO in this subject:
A) Is approximately 4.5% 
B) Cannot be calculated until 30 measurements have been made 
C) Suggests that the patient may have asthma 
D) Indicates that the DLCO system displays excessive variability

Quizplus · Accepted Answer

The coefficient of variation (CV) is a measure of relative variability, calculated as the standard deviation divided by the mean, expressed as a percentage. In this case, the CV cannot be calculated until 20 measurements have been made, but it is given that the DLCO measurements were taken on 20 consecutive days. As the question does not mention any abnormal results or variability in the DLCO measurements, we can assume that the measurements were consistent and well-controlled. Therefore, the CV is a valid measure and can be calculated. A CV of approximately 4.5% indicates that the DLCO measurements were relatively stable, with only a small amount of variability. It is unlikely that this variability is due to asthma or problems with the DLCO system.

A Biologic Control Subject Performs DLCO Measurements on 20 Consecutive