Module 6: Intro to Quality Control

Question 1

TQM

Answer 1

Total quality management

overall management of all quality processes and outcomes with the goal of long term customer satisfaction

Question 2

QM

Answer 2

quality management

includes stages QS, QA, QC with a focus on financial impact of quality activities

Question 3

QS

Answer 3

quality system

comprehensive and coordinated efforts to maintain and improve lab processes to meet quality goals

Question 4

QA

Answer 4

quality assurance
planned and systematic activities to provide confidence that an organization fulfills quality requirement
QA monitors QC data and looks for opportunities to improve processes

Question 5

QC

Answer 5

quality control

includes regular operational activities that ensure high quality test results

Question 6

Intent of QC

Answer 6

identify and prevent issues

Question 7

Statistical QC

Answer 7

monitors the performance of analytical methods by analyzing samples with known concentrations of analytes (ex. controls)
compare observed values with known values

Question 8

Non Statistical QC

Answer 8

procedures to maintain and improve the performance of analytical systems

Question 9

examples of nonstatistical QC

Answer 9

production and monitoring of high quality water for procedures
regular calibration of equipment, glassware, pipets, procedures
ensuring stability of power supply
monitoring temp of baths, fridge, freezer, centrifuge
performance and documentation of maintenance and troubleshooting
monitor prep and storage of reagents and standards
performance of linearity checks

Question 10

Analytical system

Answer 10

procedure, reagents, calibrators, instrument

Question 11

preventative maintenance

Answer 11

done to prevent development of problems

chemical buildup, corrosion, worn/damaged parts

Question 12

calibration

Answer 12

process of analyzing known sampled of difference concentrations to make a curve

Question 13

standard

Answer 13

material or solution of known concentration

Question 14

3 types of error

Answer 14

pos (higher) or negative (lower)
random error
systemic

Question 15

Error

Answer 15

difference between the true value and the measured value

Question 16

accuracy

Answer 16

the nearness of a result to its true value

Question 17

precision

Answer 17

the reproducibility of replicate measurements

Question 18

Sensitivity

Answer 18

ability to measure low concentrations (minimal detection limit)

Question 19

specificity

Answer 19

ability of an analytical system to accurately measure one analyte without interference from other substances

Question 20

measures of central tendancy

Answer 20

mean, median, mode

Question 21

mean

Answer 21

average of a set of values

Question 22

median

Answer 22

the middle number in a set of data arranged in increasing numerical data
ex: 1,4,6,8,9
median = 6

Question 23

mode

Answer 23

value that occurs most frequently in a data set
ex: 1,5,3,5,6,5
mode=5

Question 24

SD or s

Answer 24

standard deviation
statistic that describes the dispersion or spread of a set of measurement about the mean of a Gaussian or normal distribution
Measurement of imprecision

Question 25

Coefficient of Variation (%CV)

Answer 25

standard deviation expressed as a percentage of the mean another way to describe precision of a method No units, can be used to compare the precision of other methods CV=(s/X)100 s=standard deviation X=mean

Question 26

the lower the %CV, the ______ the precision

Answer 26

better

Question 27

Distribution

Answer 27

the spread and shape of a frequency curve | one type is the Gaussian curve

Question 28

Gaussian distribution or curve (normal)

Answer 28

a symmetrical bell-shaped distribution whose shape is given by a specific equation in which the mean and standard deviation are variables mean=median=mode at top of bell curve

Question 29

non Gaussian distribution

Answer 29

a distribution that does not follow a bell-shaped curve SD would not be a valid statistic mean does not equal median does not equal mode

Question 30

Control

Answer 30

known concentration measured values are compared to a range of acceptable values fall within range = assumed method is working properly fall outside range = may indicate problem with the analytical system

Question 31

control materials

Answer 31

ready to use liquid form or lyophilized/freeze-dried to be reconstituted with water or diluent matrix similar to pt sample

Question 32

single analyte control

Answer 32

control only contains one analyte at a known concentration

Question 33

multi-analyte / multi-controls

Answer 33

contains a number of analytes at known concentration

Question 34

Analytical run

Answer 34

interval in which performance/precision and accuracy of the measuring system can be expected to remain stable a set time or a set # of samples Run may never exceed 24 hrs and must contain both controls and pt samples

Question 35

Control limits

Answer 35

defined limits or ranges of expected results that if exceeded, warn of an error in the system

Question 36

obtaining control limits

Answer 36

each lab makes their own limits mean and SD are calculated from data collected by running control sample under standard operating conditions (at least 1 month) Minimum of 20 observations to establish a minimum estimate

Question 37

+/- 1 SD

Answer 37

about 68% of values will fall within this range

Question 38

+/- 2 SD

Answer 38

about 95% of values will fall within this range

Question 39

+/- 3 SD

Answer 39

about 99% of values will fall within this range

Question 40

Control chart

Answer 40

graphical method plot control values to the expected results/ control limit Levey-jennings chart left y axis= control result x axis= time (days or run #) horizontal lines for the mean, +/- 1SD, +/- 2SD, +/- 3SD (written on right y axis) chart should be big enough for +/- 4SD

Question 41

Levey-jennings chart labeling (6)

Answer 41

``` name of the test name, level and lot# of control material units of measurement analytical system mean and SD time period covered by chart ```

Question 42

if qc data is outside of +/-2 SD on levey Jennings chart

Answer 42

circle plot of graph in red and then trouble shoot (and document troubleshooting)

Question 43

Troubleshooting (FIRED)

Answer 43

F: figure out what is going on (check for errors/flags, other controls ran on that instrument, recent maintenance, reagent and calibration logs) I: Isolate the cause (RITE) R: Resolve the issue (correct issues) E: evaluate the resolution (repeating controls, if control is good, repeat all pt samples from failed run) D: Document all steps and outcomes

Question 44

Troubleshooting: Isolate the cause (RITE)

Answer 44

R: Reagents (new, expired, incorrectly prepared/stored, calibrators, diluents, washes) I: instrument (dirty, damaged, new components, bubbles, leaks, precipitates, unstable temp or power supply) T: technologist (error loading controls, operation, technique, fail to comply with maintenance/calibration schedule) E: environment (room temp, humidity, power, fumes)