Statistics and QC

Question 0

The conformance to the requirements of users or customers

Answer 0

quality

Question 1

includes all systematic actions planned and implemented to provide adequate confidence that test results and services satisfy the needs of the patient

Answer 1

quality assurance

Question 2

This includes the analytical phase of testing

Answer 2

quality control

Question 3

defined as all procedures inside and outside the laboratory that precede the test process

Answer 3

pre-analytical quality assurance

Question 4

defined as all processes performed at the instrument to assure correct test results

Answer 4

analytical quality assurance

Question 5

defined as all processes performed after the laboratory report leaves the laboratory

Answer 5

post-analytical quality assurance

Question 6

Factors include: correct ordering of tests, preparation of the patient, correct patient ID, proper collection of the sample, timely transport to the lab, proper handling from collection to analysis, and proper handling within the laboratory

Answer 6

pre-analytical quality assurance factors

Question 7

Factors include: use of internal and external QC programs, use of monitor sheets requiring written verification of completeness, proper labeling and use of reagents, preventative maintenance procedures for the instruments, documentation of temps for refrigerators/heat blocks, accuracy checks for balances and thermometers, current procedure manuals, and current safety procedures

Answer 7

Analytical quality assurance factors

Question 8

Factors include: reference range selection, documentation of clerical errors, timely reporting of results, verification of calculations on final reports, a review process of final results for transcription errors, verification of a user friendly report, timely turnaround time, correct result interpretation by the caregiver, and assurance that lab tests results in appropriate patient care

Answer 8

post-analytical quality assurance factors

Question 9

These are used to monitor the precision and accuracy of a method; used to validate whether the instrument or method is reliable, therefore patient results are also reliable; include a range of numbers

Answer 9

controls

Question 10

these are used in the analytical process to standardize the method or instrument; has an exact amount or one given value

Answer 10

standards

Question 11

these are determined by dissolving a weighed amount of standard material in an appropriate solvent and diluting to a stated volume or mass

Answer 11

primary calibration standard

Question 12

this is what standard we use in the lab where the concentration or other quantity is determined by an analytical method of stated reliability. Standard is prepared, then analyzed to determine the value of the standard, and then purchased by our lab.

Answer 12

secondary standard

Question 13

What are the three general guidelines NCCLS provides concerning concentrations and number of control materials to test per day?

Answer 13

1 the number and conc. should be sufficient to cover the range of interest
2 a minimum of two concentration levels of controls is recommended and chosen to correspond to clinical decision levels if possible
3 the control levels chosen should reflect values seen in patient specimens in the lab

Question 14

What are 8 desirable features of quality control materials?

Answer 14

1 analyte conc. at medically significant levels
2 control matrix as much like the human specimen as possible
3 control material stability of 1 year if possible for unopened material
4 stability after opening or reconstitution
5 low vial to vial variation
6 available in large batches
7 material is ready to use or requires minimal preparation
8 material is reasonably priced

Question 15

this is a control which has been prepared or purchased with a stated or expected value; used with a small number of tests; expensive

Answer 15

assayed control

Question 16

this is a control whose value is not known except when assayed within the laboratory by repeated testing; used for a large quantity of tests in a large lab; less expensive

Answer 16

unassayed controls

Question 17

the spread or dispersion of values studied

Answer 17

distribution

Question 18

illustrates dispersion graphically displayed as XY plots, bar graphs, or histograms

Answer 18

distribution curve

Question 19

this is represented by a “bell-shaped” curve or a symmetrical spread of data about a central location

Answer 19

normal distribution

Question 20

limits between which a specified proportion of a population is expected to lie with respect to a measured characteristic

Answer 20

confidence limits

Question 21

refers to the odds that a value equal to or larger than the one obtained would occur by chance alone

Answer 21

probability

Question 22

What is the percentage of observations expected to lie within one SD?

Answer 22

68.2%

Question 23

What is the percentage of observations expected to lie within two SD?

Answer 23

95.5%

Question 24

What is the percentage of observations expected to lie within three SD?

Answer 24

99.7%

Question 25

What is the confidence limit used in the clinical lab?

Answer 25

95.5%

Question 26

the arithmetic average value calculated as the sum of all individual values divided by the number of observations; it is an indicator of central tendency and is therefore related to accuracy or systematic error

Answer 26

mean

Question 27

the value found at the center of all the observations, with an equal number of observations above and below it

Answer 27

median

Question 28

the value in the sample or population which occurs with the greatest frequency

Answer 28

mode

Question 29

the difference or spread between the highest and lowest values or observations in the sample; provides the simplest definition of dispersion

Answer 29

range

Question 30

the square root of the average squared deviation from the mean; measures spread or distribution of a group of data around the mean; measures the width of distribution and is related to imprecision or random error

Answer 30

standard deviation

Question 31

a measure of the variability about the mean or SD^2

Answer 31

variance

Question 32

the standard deviation expressed as a percentage of the mean; (SD/mean) x 100

Answer 32

coefficient of variation (CV)

Question 33

What are two uses of calculating SD?

Answer 33

1 measures spread or distribution of a group of data around the mean
2 measures the width of the distribution and is related to imprecision or random error

Question 34

What 3 statistics describe central tendency?

Answer 34

mean, median, and mode

Question 36

What 3 statistics describe variability about the mean?

Answer 36

range, standard deviation, and variance

Question 37

Includes pre-analytical, analytical, and post-analytical factors, such as verification of sample collection quality, sample processing procedures, test method selection, reporting of results, and interpretation of the final report.

Answer 37

quality assurance

Question 38

Includes pre-analytical, analytical, and post-analytical factors, such as verification of sample collection quality, sample processing procedures, test method selection, reporting of results, and interpretation of the final report.

Answer 38

quality assurance