Question

The RDW index is expressed by which of the following equation?

(a) [(20th – 80th) Percentile Volume / (20th + 80th) Percentile Volume] X 100 X K

(b) [(20th + 80th) Percentile Volume / (20th – 80th) Percentile Volume] X 100 X K

(c) [(20th – 80th) Percentile Volume / (20th – 80th) Percentile Volume] X 100 X K

(d) [(20th + 80th) Percentile Volume / (20th + 80th) Percentile Volume] X 100 X K

I got this question in an internship interview.

Question is taken from Biofeedback Instrumentation in portion Biomedical Recorders of Biomedical Instrumentation

Answer 1

Correct choice is (a) [(20th – 80th) Percentile Volume / (20th + 80th) Percentile Volume] X 100 X K

The explanation: The RDW index is expressed by the following equation [(20th – 80th) Percentile Volume / (20th + 80th) Percentile Volume] X 100 X K. It is a numerical expression of the width of the size distribution of red cells. It is derived by analog computation. The total erythrocyte count is scanned by a continuously variable thresholding circuit. The upper threshold is moved progressively lower from a level equivalent to 360 femolitres until 20 percent of all erythrocytes present have a size above a certain value.