Which analyte has the poorest precision given the following data?

To determine which analyte has the poorest precision, it’s essential to assess the variability in each measurement relative to the average value. Precision is often evaluated using the coefficient of variation (CV), which is calculated as the standard deviation divided by the mean, usually expressed as a percentage.

For the calcium (Ca) measurement, the average is 2.5 with a standard deviation of 0.3. The CV would be calculated as follows:

[ \text{CV} = \left( \frac{0.3}{2.5} \right) \times 100 = 12% ]

For potassium (K), with an average of 4.0 and a standard deviation of 0.4, the calculation would be:

[ \text{CV} = \left( \frac{0.4}{4.0} \right) \times 100 = 10% ]

For sodium (Na), averaging 140 with a standard deviation of 4.0, the CV can be computed as:

[ \text{CV} = \left( \frac{4.0}{140} \right) \times 100 \approx 2.86% ]

And