The Correct Answer is B) Precision
The degree of agreement among individual results of a homogeneous sample under the same conditions is definitively known as precision. 1
Definition and Core Concept
Precision specifically measures the closeness of agreement of replicate test results under stipulated conditions. 1 This encompasses:
- Repeatability (within-run precision): The degree to which the same result is obtained when testing the same sample multiple times under identical conditions—same operator, same instrument, same run 1
- Reproducibility (between-run precision): The degree to which the same result is obtained when conditions vary—different operators, different runs, different instruments, or different sites 1
Why the Other Options Are Incorrect
Accuracy (Option A)
- Accuracy refers to the closeness of agreement between a measured value and the true value, not agreement among replicate measurements 1, 2
- Accuracy is an aggregate measure that incorporates both precision (variability) and bias (systematic error) 2
- A test can be highly precise (consistent results) but still inaccurate if there is systematic bias 2
Specificity (Option C)
- Specificity measures the proportion of subjects without the target condition in whom the test result is negative 1
- This is a diagnostic performance characteristic, not a measure of measurement reproducibility 1
Linearity (Option D)
- Linearity refers to the ability to provide results directly proportional to the amount of analyte in the test sample within a given measuring range 1
- This describes the relationship between analyte concentration and test response, not reproducibility of measurements 1
Clinical Context
Precision is typically expressed numerically by measures of imprecision, including standard deviation, variance, or coefficient of variation under specified measurement conditions 1. Understanding precision is essential for: