Method Evaluation & Quality Control

Question 1

is used to verify the acceptability of new

methods prior to reporting patient results.

Answer 1

method evaluation

Question 2

The foundation for monitoring performance (known

as QC)

Answer 2

descriptive statistics

Question 3

The three most commonly used descriptions of the center of a data set

Answer 3

Mean, median, mode

Question 4

There are four commonly used descriptions of

spread:

Answer 4

Range, SD, CV, SDI

Question 5

the most frequently used

measure of variation.

Answer 5

SD

Question 6

represent the “average” distance from the center of the

data (the mean) and every value in the data set.

Answer 6

CV

Question 7

a calculation to show the number of SDs a value is from the target mean.

Answer 7

SDI

Question 8

Three

factors are generated in a linear regression

Answer 8

Slope, y-intercept, correlation coefficient (r)

Question 9

is a measure of the strength of the

relationship between the two methods.

Answer 9

correlation coefficient (r)

Question 10

indicates that both variables increase and

decrease together,

Answer 10

positive r

Question 11

indicates that as one variable increases,

the other decreases.

Answer 11

negative r

Question 12

An r value of ___ indicates no relationship,

Answer 12

0

Question 13

r = ___

indicates a perfect relationship.

Answer 13

1.0

Question 14

An alternate approach to visualizing paired data is the difference plot, which
is also known as the:

Answer 14

Bland-Altman plot

Question 15

The difference between test and reference method results is called

Answer 15

error

Question 16

is present in all measurements and can be either
positive or negative, typically a combination of both positive and negative errors
on both sides of the assigned target value.

Answer 16

Random error

Question 17

influences observations consistently in one direction

higher or lower

Answer 17

Systematic error

Question 18

exists when there is a
continual difference between the test method and the comparative method
values, regardless of the concentration.

Answer 18

Constant systematic error

Question 19

exists when the differences between the test
method and the comparative method values are proportional to the analyte
concentration.

Answer 19

Proportional error

Question 20

TRUE/FALSE: The CLIA final rule requires

that waived tests simply follow the manufacturer’s instructions.

Answer 20

TRUE

Question 21

Systematic error can be due to constant or proportional error and is estimated
from three types of study:

Answer 21

recovery, interference, and COM

Question 22

Ability of a method to detect small quantities or

small changes in concentration of an analyte.

Answer 22

Analytic sensitivity

Question 23

Ability of a method to detect only the analyte it is

designed to determine, also known as cross-reactivity.

Answer 23

Analytic specificity

Question 24

Also known as linear or dynamic
range. Range of analyte concentrations that can be directly measured
without dilution, concentration, or other pretreatment.

Answer 24

AMR (analytic measurement range)

Question 25

Range of analyte that a method can quantitatively report, allowing for dilution, concentration, or other pretreatment used to extend AMR.

Answer 25

CRR (clinically reportable range)

Question 26

Method evaluation begins with a _____

Answer 26

precision study

Question 27

Ability of an analytic test to measure a known amount of | analyte; a known amount of analyte is added to real sample matrices.

Answer 27

Recovery

Question 28

``` Effect of (a) compound(s) on the accuracy of detection of a particular analyte. ```

Answer 28

Interference

Question 29

``` Body component (e.g., fluid and urine) in which the analyte is to be measured. ```

Answer 29

Matrix

Question 30

The purpose of this type of study is to determine how much of the analyte can be detected (recovered) in the presence of all the other compounds in the matrix.

Answer 30

Recovery studies

Question 31

examines patient samples by the method being | evaluated (test method) with a reference method.

Answer 31

COM studies

Question 32

designed to determine if specific compounds affect the | accuracy of laboratory tests.

Answer 32

Interference studies

Question 33

A nonparametric regression method for | comparison studies. It is a robust method that is resistant to outliers.

Answer 33

Passing-Bablok regression

Question 34

Linear regression analysis (orthogonal least squares) used to compare two methodologies using the best fit line through the data points

Answer 34

Deming regression

Question 35

Defines the strength of relationship | between two variables.

Answer 35

Correlation Coefficient (r)

Question 36

Indicates the proportion of | variation explained by one variable to predict another.

Answer 36

Coefficient of Determination (r2 or R2)

Question 37

determined for each test based on the amount of error that will not negatively affect clinical decisions.

Answer 37

Allowable error

Question 38

in the laboratory involves the systematic monitoring of analytic processes to detect analytic errors that occur during analysis and to ultimately prevent the reporting of incorrect patient test results.

Answer 38

Quality Control

Question 39

Threshold at which the value is statistically unlikely.

Answer 39

Control limits

Question 40

Material analyzed only for QC purposes.

Answer 40

Control material

Question 41

QC for general chemistry assays generally uses ____ levels of control, while immunoassays commonly use ____.

Answer 41

two;three

Question 42

TRUE/FALSE: The underlying rationale for running repeated assays is to detect random errors that affect precision.

Answer 42

TRUE

Question 43

With a new instrument or with new lots of control material, the different levels of control material must be analyzed for ____ DAYS

Answer 43

20

Question 44

are the criteria used to decide that a given method meets the clinical requirements.

Answer 44

QC specifications

Question 45

“voice of the customer” “the performance the health care provider needs”

Answer 45

QC specifications

Question 46

“voice of the process” “natural variation of a given test”

Answer 46

QC limits

Question 47

A pair of medical decision points that span the | limits of results expected for a defined healthy population.

Answer 47

Reference interval

Question 48

Subject preparation, prescription medications, collection time, sample storage, stress, food/beverage ingestion

Answer 48

Preanalytic factors

Question 49

Precision, accuracy, lot to lot reagents, linearity, interference, recovery

Answer 49

Analytic factors

Question 50

Statistical test that makes no specific | assumption about the distribution of data.

Answer 50

Nonparametric method

Question 51

Statistical test that assumes the observed values, or some mathematical transformation of those values, follow a (normal) Gaussian distribution

Answer 51

Parametric method

Question 52

To establish a reference interval, it is recommended that the study includes at least ____ individuals.

Answer 52

120

Question 53

1. Changes in reagent formulations by the vendor 2. Minor changes in reagents due to lot to lot variations 3. Differences between reference interval & test popuations-selection bias

Answer 53

Common Problems Encountered when Monitoring | Reference Intervals

Question 54

Ability of a test to detect a given disease or | condition.

Answer 54

Diagnostic sensitivity

Question 55

Ability of a test to correctly identify the absence | of a given disease or condition.

Answer 55

Diagnostic specificity

Question 56

Chance of an individual having a given | disease or condition if the test is abnormal.

Answer 56

Positive predictive value

Question 57

Chance an individual does not have a given | disease or condition if the test is within the reference interval.

Answer 57

Negative predictive value

Question 58

To define an appropriate cutoff, laboratorians often use a graphical tool called the:

Answer 58

receiver operator characteristic (ROC)

Question 59

can be used to determine the most efficient cutoff for | a test and are an excellent tool for comparing two different tests.

Answer 59

ROC curves