Chemistry Ch. 3

Front 1

accuracy

Back 1

without error; closeness to the true value

Front 2

method evaluation

Back 2

used to verify the acceptability of new methods prior to reporting patient results

Front 3

What is important to determine before implementing a new test?

Back 3

it is important to determine if the test is capable of performing acceptably

Front 4

descriptive statistics

Back 4

Data in the clinical laboratory summarized to monitor test performance. The foundation for monitoring performance (known as QC)

Front 5

When comparing and analyzing collections or sets of laboratory data, patterns can be described by..?

Back 5

described by their center, spread, or shape

Front 6

assessment of data dispersion, or spread, allows what?

Back 6

allows laboratorians to assess the predictability (and lack of) in a laboratory test or measurement

Front 7

The three most commonly used descriptions of the center of a dataset are?

Which is the most common?

Back 7

The mean, the median, and the mode

The mean is the most common

Front 8

After describing the center of a dataset, what is very useful to do next?

Back 8

it is very useful to indicate how the data are distributed (spread)

The spread represents the relationship of all the date points to the mean

Front 9

What are 3 commonly used descriptions of a spread?

which is the easiest measure of spread to understand?

which is used most frequently used to measure variation?

Back 9

1. Range

2. standard deviation (SD)

3. coefficient of variation (CV)

The range

SD

Front 10

Although there are many different "shapes" or distributions that datasets can exhibit, the most commonly discussed one is the Gaussian distribution.

What is the Gaussian distribution?

Back 10

described many continuous laboratory variables and shares several unique characteristics: the mean, median, and mode are identical; the distribution is symmetrical (this symmetrical shape is often called a "bell curve")

Front 11

What is a COM and what does it stand for?

Back 11

comparison of methods, to compare two different methods

a COM experiment involves measuring patient specimens by both an existing (reference) method and a new (test) method.

Front 12

linear regression analysis

Back 12

a statistical technique that provides objective measures of the location and dispersion for the line

y=mx+b

Front 13

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

What does it mean?

Back 13

Bland-Altman plot

This indicates either the percent or absolute bias (difference) between the reference and test method values over the average range of values

Front 14

What is the difference between test and reference method results called?

Back 14

error

Front 15

What are the two kinds of error measured in COM (comparison of methods) experiments and what do they mean?

Back 15

Random error: error varies from sample to sample. Can be a result of many factors including instrument, operator, reagent, and environmental variations.

Systemic error: influences observations consistently in one direction (higher or lower). Error always in one direction. The measures of slope and y-intercept provide estimates of the systemic error.

Front 16

What can systemic error be broken down into?

Back 16

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

Proportional error- exists when the differences between the test method and the comparative method values are proportional to the analyte concentration

Front 17

Inferential statistics

Back 17

used to draw conclusions (inferences) regarding the means or SD's of two sets of data

Front 18

What does the FDA regulate?

Back 18

regulates laboratory instruments and reagents

Front 19

What does the CMS (the centers for Medicare and Medicaid services) regulate?

Back 19

Regulates the clinical laboratory improvement amendments (CLIA)

Front 20

Why select a new method of testing?

Back 20

to reduce cost,

improve the quality of results

increase client satisfaction

improve efficiency

Front 21

Standard

Back 21

a substance or solution in which the concentration is determined. It is used in calibration of an instrument or method

Front 22

Imprecision

Back 22

dispersion of repeated measurements about the mean due to analytic error

Front 23

Inaccuracy

Back 23

difference between measured value and its true value due to systemic error, which can be either constant or proportional

Front 24

total error

Back 24

random error plus systemic error

Front 25

precision

Back 25

estimates the random error associated with the test method and detects any problems affecting its reproducibility

Front 26

Accuracy is determined using three types of studies:

Back 26

1. recovery

2. interference

3. patient sample comparison

Front 27

Recovery studies

Back 27

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

Front 28

Interference studies

Back 28

effect of (a) compound(s) on the accuracy of detection of a particular analyte

Front 29

matrix

Back 29

body component (fluid and urine) in which the analyte is to be measured

Front 30

allowable (analytic) error

Ea

Back 30

based on the amount of error that will not negatively affect clinical judgments

Front 31

multirule procedure

Back 31

decision criteria to determine if an analytic run is in control; used to detect random and systemic error over time

Front 32

what is a common way to assess the determination of control materials over time?

Back 32

the use of a Levey -Jennings control chart

Front 33

proficiency test

Back 33

method used to validate a particular measurement process. the results are compared with other external labs to give an objective indication of test accuracy

Front 34

proficiency samples

Back 34

specimens that have known concentrations of an analyte for the test of interest. the testing lab does not know the targeted concentration when tested

Front 35

reference intervals are sometimes erroneously called...?

Back 35

normal ranges

Front 36

bias

Back 36

difference between the observed mean and the reference mean

Front 37

diagnostic sensitivity

Back 37

ability of a test to detect a given disease or condition

Front 38

diagnostic specificity

Back 38

ability of a test to correctly identify the absence of a given disease or condition

Front 39

analytic sensitivity vs. clinical sensitivity

Back 39

analytic: refers to the lower limit of detection for a given analyte

Clinical: refers to the proportion of individuals with that disease who test positively for the test

Front 40

limit of detection

Back 40

lowest amount of analyte accurately detected by method

Front 41

positive predictive value

Back 41

chance of an individual having a given disease or condition if the test is abnormal

Front 42

negative predictive value

Back 42

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

Front 43

shift

Back 43

a sudden change in data and the mean

Front 44

trend

Back 44

a gradual change in data and the mean

Front 45

Clinically reportable range (CRR)

Back 45

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

Front 46

analytic measurement range (AMR)

Back 46

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