1.17: Quality Control

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In establishing the 95% confidence limits for a particular method for a quality control program, one would expect how many test results to fall beyond the limits of allowable variation by chance?:
1. one in 95
2. one in 5
3. one in 10
4. one in 20
5. one in 30
A laboratory test has ± 2 SD control limits of ± 5. The mean, target value is 15. How many days was the method out of control during the two week period shown?:
1. 1
2. 2
3. 3
4. 4
5. 5

Day	1	2	3	4	5	6	7	8	9	10
Value	11	13	18	7	22	28	15	14	26	14

The 68% confidence limits of a glucose control are 750-850 mg/L. A control and a series of patient specimens are run. The control reads 750 mg/L. If control results must be within ± 2 SD, what action should you take?:
1. report out patient results, since control results are within acceptable limits
2. repeat the control, since control results are out of control; if repeat results are in control, report out patient results
3. repeat both the control and all patient specimens using same methodology
4. repeat both the control and all patient specimens using different methodology
5. run second control if within range, report patient results
A medical technologist should never use the pattern of patient results, i.e. abnormal values, as an indicator of instrument performance.
1. true
2. false

Use the following Key to answer Questions 5-7:

1, 2, and 3 are correct
1 and 3 are correct
2 and 4 are correct
4 only is correct
all are correct

Which of the following is/are acceptable quality control pool material?
1. frozen
2. lyophilized
3. low temperature liquid
4. fresh patient samples
When performing an analysis on a stat. analyzer, a quality control sample should be run:
1. during the first shift
2. depending upon the proven stability of the test system
3. by each technologist
4. usually at least once every 8 hour shift
If the quality control sample is out of range (>3 SD), the technologist should:
1. recalibrate the instrument
2. troubleshoot the instrument
3. record the out-of-range result on the QC chart
4. notify the supervisor if the problem cannot be solved within 30 minutes
Calibrators may be used as quality control pools if:
1. the usual quality control pools are expired
2. the usual quality control pools just won’t ‘come in range’
3. there is a temporary shortage of the usual quality control pools
4. there are no quality control materials that contains the analyte
5. never

Answer

d (p. 390)
b (p. 391)
a (p. 346, 391)
b (p. 392)
a (p. 388)
c (p. 387-388, 399)
e (p. 393)
d (p. 396)