When inspecting an internal quality-control plot for a blood gas ...

[RYAN BANYAN]

When inspecting an internal quality-control plot for a blood gas analyzer, you notice several data points sporadically appearing outside the 2 standard deviation (SD) range. This represents what type of analytic error?
 
  1. Random error
  2. Bias
  3. Imprecision
  4. Systematic error
  a. 1 and 3 only
  b. 2 and 4 only
  c. 1, 2, and 4 only
  d. 1, 2, 3, and 4

Question 2

Statistically derived limits for internal quality control of blood gas samples are usually set at what appropriate level?
 
  a. 1 standard deviation from the mean
  b. 2 standard deviations from the mean
  c. 3 standard deviations from the mean
  d. 5 standard deviations from the mean

[miss.ashley]

Answer to Question 1

ANS: A
There are two categories of analytical error: (1) random and (2) systematic. Random error is ob-served when sporadic, out-of-range data points occur (see Figure 19-9, point A). Random errors are errors of precision or, more precisely, imprecision.

Answer to Question 2

ANS: B
In one common approach, the results of control media analyses are plotted on a graph and com-pared with statistically derived limits, usually 2 standard deviation (SD) ranges (see Figure 19-9).