Deck 26: Evaluation of Methods

Question 1

Random error is associated with ______, and systematic error is associated with ______.The degree of ______ is described by the standard deviation or the coefficient of variation.

A)imprecision, inaccuracy, imprecision
B)imprecision, inaccuracy, inaccuracy
C)inaccuracy, imprecision, imprecision
D)inaccuracy, imprecision, inaccuracy

Answer 1

imprecision, inaccuracy, imprecision

Question 2

In judging analytical performance in the laboratory for a new method, it was found that the 95% upper limit of an error is smaller than the allowable error.It was also found that the 95% lower limit of error is greater than the allowable error.In this situation, what should the response of the technologist be?

A)The method should be rejected.
B)The method should be modified to improve its analytical performance.
C)The method is acceptable and can be used.
D)Both a and b

Answer 2

Both a and b

Question 3

It has been proposed that allowable error be either ______ or ______ of the reference range for an analyte, whichever is less.For enzymes, the limit is ______.

A) , 10%, 20%
B) , 20%, 10%
C) , 20%, 10%
D) , 10%, 20%

Answer 3

, 10%, 20%

Question 4

New analytical methods are usually developed to:
1)improve accuracy over existing methods.
2)allow automation.
3)increase labor in the laboratory.
4)reduce reagent costs.

A)1, 2, 3, 4
B)1, 2, 3
C)1, 2, 4
D)2, 3, 4

Question 5

Even when a method's performance is well documented by published evaluation studies, the new laboratory considering use of the method should evaluate ______ and perform ______ to verify acceptable performance in that laboratory.

A)random analytical error, the comparison-of-methods experiment
B)random analytical error, the recovery experiment
C)constant systematic error, the comparison-of-methods experiment
D)constant systematic error, the recovery experiment

Question 6

A method that falls in the six Sigma region of the Medical Decision Chart indicates that the relationship between the performance of the method and quality control is such that:

A)one to two quality-control measures per run are required.
B)two to three quality-control measures per run are required.
C)three to four quality-control measures per run are required.
D)four to six quality-control measures per run are required.

Question 7

Usually a method-evaluation study is performed to:

A)test all methods to determine the method with the smallest error.
B)determine whether the selected method has acceptably small analytical errors.
C)both a and b
D)neither a nor b

Question 8

Which of the following factors can contribute to random analytical errors?

A)instability of the instrument
B)variability in handling techniques such as pipetting
C)variations in the reagents and calibrators
D)all of the above

Question 9

The limit of detection:
1)is the minimum concentration of analyte whose presence can be qualitatively detected under defined conditions.
2)is the concentration at which an observed value will be very likely to exceed the limit of the blank.
3)is the highest value of a zero sample.
4)is the minimum concentration of analyte whose presence can be quantifiably measured reliably under defined conditions.

A)1, 2
B)2, 3
C)3, 4
D)1, 3, 4

Question 10

All of the following describe the within-run replication experiment except:

A)It is the simplest type of study.
B)It measures the constant systematic error caused by the presence of a substance suspected of interfering with the test method.
C)It allows assessment of precision over a very short time.
D)It should be performed with samples whose matrix is as similar as possible to that of the intended patient samples.

Question 11

When considering application characteristics, emphasis may be placed on ______ for pediatric applications, on ______ for stat applications, and on ______ for high-volume screenings.

A)sample size, turnaround time and interrupt features, sample throughput rate
B)turnaround time and interrupt features, sample throughput rate, sample size
C)sample throughput rate, sample size, turnaround time and interrupt features,
D)turnaround time and interrupt features, sample size, sample throughput rate

Question 12

Which of the following statements is/are true regarding the correlation coefficient?

A)A value of zero indicates that there is no correlation between the methods.
B)A value of +1 indicates perfect positive correlation.
C)This coefficient is extremely sensitive to the range of analyte concentrations of the patient specimens in the comparison-of-methods experiment.
D)All of the above are true of the correlation coefficient.

Question 13

Calculate the percentage recovery given the following information:
Baseline sample preparation: 1.5 mL serum + 0.25 mL water
Spike sample preparation: 1.5 mL serum + 0.25 mL 5000 mg/L standard
Baseline sample measured concentration: 950 mg/L
Spiked sample measured concentration: 1621 mg/L

A)89%
B)94%
C)98%
D)106%

Question 14

Interference should be evaluated for all commonly encountered interferents such as:

A)hemolysis
B)lipemia
C)icterus
D)all of the above

Question 15

Regression analysis of two methods produced the equation y = 0.137 + 0.813x.The proportionality between the two methods is:

A)the calculated value for y given the value for x
B)the calculated value for x given the value for y
C)0.137
D)0.813

Question 16

Which of the following is the correct sequence to follow in method selection?

A)define requirements, review literature, determine need, select candidate methods
B)determine need, define requirements, review literature, select candidate methods
C)select candidate methods, determine need, define requirements, review literature
D)determine need, review literature, define requirements, select candidate methods

Question 17

The within-run component of variation is caused by:
1)sampling and pipetting precision.
2)short-term variations in temperature of the instrument.
3)instability of the calibration curve.
4)short-term variations in the stability of the instrument.

A)1, 2, 3, 4
B)1, 2, 3
C)1, 2, 4
D)2, 3, 4