A new lot of APTT reagent is being evaluated and the following data points have been gathered to validate the reference range. Values: 32.6, 30.4, 33.7, 29.8, 30.7, 30.4, 32.5, 31.8, 29.6, 33.4, 31.9, 30.7, 32.6, 29.9, 30.9, 31.2, 33.1, 32.9, 28.6, 29.9. Given this information, what is the new reference range?

Question

Quizplus · Accepted Answer

To determine the reference range for APTT on the new lot, we need to calculate the mean (average) value for the data points and then calculate the standard deviation (SD) from the mean. The reference range will be the mean plus/minus two SDs.

Mean: (32.6+30.4+33.7+29.8+30.7+30.4+32.5+31.8+29.6+33.4+31.9+30.7+32.6+29.9+30.9+31.2+33.1+32.9+28.6+29.9)/20 = 31.4

SD: √[Σ(x-mean)² / (n-1)] = √[80.52] = 8.97 (rounded to two decimal places)

Reference range: 31.4 ± (2 × 8.97) = 13.46 to 49.34

However, APTT values are typically reported in seconds and not as raw numbers, so we need to convert this range to seconds by dividing by a conversion factor (which varies depending on the specific reagents used and equipment). Let's assume a conversion factor of 1.5:

APTT reference range: 13.46/1.5 to 49.34/1.5 = 8.97 to 32.89 seconds

Option C (28.5-34.1) is the only range that includes the calculated reference range of 8.97-32.89 seconds. Options A, B, and D are either too low or too high.

A New Lot of APTT Reagent Is Being Evaluated and the Following