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Clinical Chemistry > Method Evaluation & Quality Control > Flashcards

Method Evaluation & Quality Control Flashcards

1
Q

is used to verify the acceptability of new

methods prior to reporting patient results.

A

method evaluation

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2
Q

The foundation for monitoring performance (known

as QC)

A

descriptive statistics

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3
Q

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

A

Mean, median, mode

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4
Q

There are four commonly used descriptions of

spread:

A

Range, SD, CV, SDI

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5
Q

the most frequently used

measure of variation.

A

SD

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6
Q

represent the “average” distance from the center of the

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

A

CV

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7
Q

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

A

SDI

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8
Q

Three

factors are generated in a linear regression

A

Slope, y-intercept, correlation coefficient (r)

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9
Q

is a measure of the strength of the

relationship between the two methods.

A

correlation coefficient (r)

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10
Q

indicates that both variables increase and

decrease together,

A

positive r

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11
Q

indicates that as one variable increases,

the other decreases.

A

negative r

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12
Q

An r value of ___ indicates no relationship,

A

0

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13
Q

r = ___

indicates a perfect relationship.

A

1.0

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14
Q

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

A

Bland-Altman plot

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15
Q

The difference between test and reference method results is called

A

error

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16
Q

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.

A

Random error

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17
Q

influences observations consistently in one direction

higher or lower

A

Systematic error

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18
Q

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

A

Constant systematic error

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19
Q

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

A

Proportional error

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20
Q

TRUE/FALSE: The CLIA final rule requires

that waived tests simply follow the manufacturer’s instructions.

A

TRUE

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21
Q

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

A

recovery, interference, and COM

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22
Q

Ability of a method to detect small quantities or

small changes in concentration of an analyte.

A

Analytic sensitivity

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23
Q

Ability of a method to detect only the analyte it is

designed to determine, also known as cross-reactivity.

A

Analytic specificity

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24
Q

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

A

AMR (analytic measurement range)

25
Q

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

A

CRR (clinically reportable range)

26
Q

Method evaluation begins with a _____

A

precision study

27
Q

Ability of an analytic test to measure a known amount of

analyte; a known amount of analyte is added to real sample matrices.

A

Recovery

28
Q 
Effect of (a) compound(s) on the accuracy of detection of
a particular analyte.
A

Interference

29
Q 
Body component (e.g., fluid and urine) in which the analyte is
to be measured.
A

Matrix

30
Q

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.

A

Recovery studies

31
Q

examines patient samples by the method being

evaluated (test method) with a reference method.

A

COM studies

32
Q

designed to determine if specific compounds affect the

accuracy of laboratory tests.

A

Interference studies

33
Q

A nonparametric regression method for

comparison studies. It is a robust method that is resistant to outliers.

A

Passing-Bablok regression

34
Q

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

A

Deming regression

35
Q

Defines the strength of relationship

between two variables.

A

Correlation Coefficient (r)

36
Q

Indicates the proportion of

variation explained by one variable to predict another.

A

Coefficient of Determination (r2 or R2)

37
Q

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

A

Allowable error

38
Q

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.

A

Quality Control

39
Q

Threshold at which the value is statistically unlikely.

A

Control limits

40
Q

Material analyzed only for QC purposes.

A

Control material

41
Q

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

A

two;three

42
Q

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

A

TRUE

43
Q

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

A

20

44
Q

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

A

QC specifications

45
Q

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

A

QC specifications

46
Q

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

A

QC limits

47
Q

A pair of medical decision points that span the

limits of results expected for a defined healthy population.

A

Reference interval

48
Q

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

A

Preanalytic factors

49
Q

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

A

Analytic factors

50
Q

Statistical test that makes no specific

assumption about the distribution of data.

A

Nonparametric method

51
Q

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

A

Parametric method

52
Q

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

A

120

53
Q
  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
A

Common Problems Encountered when Monitoring

Reference Intervals

54
Q

Ability of a test to detect a given disease or

condition.

A

Diagnostic sensitivity

55
Q

Ability of a test to correctly identify the absence

of a given disease or condition.

A

Diagnostic specificity

56
Q

Chance of an individual having a given

disease or condition if the test is abnormal.

A

Positive predictive value

57
Q

Chance an individual does not have a given

disease or condition if the test is within the reference interval.

A

Negative predictive value

58
Q

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

A

receiver operator characteristic (ROC)

59
Q

can be used to determine the most efficient cutoff for

a test and are an excellent tool for comparing two different tests.

A

ROC curves

Clinical Chemistry (9 decks)

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