STATISTICAL CONCEPTS in QUALITY CONTROL

Question 1

A statement of the extent of random variation in any series of measurement

Answer 1

STANDARD DEVIATION

Question 2

A measure of the distribution of values around the mean

Answer 2

STANDARD DEVIATION

Question 3

Square of the standard deviation

Answer 3

VARIANCE

Question 4

Used to detect significant differences between groups of data

Answer 4

VARIANCE

Question 5

Determine contributions of various factors to the total variation

Answer 5

VARIANCE

Question 6

Percentile expression of the mean

Answer 6

COEFFICIENT OF VARIATION

Question 7

Measure of the relative magnitude of variability

Answer 7

COEFFICIENT OF VARIATION

Question 8

CV = s (100)/X

Answer 8

COEFFICIENT OF VARIATION

Question 9

Reported values do not fall along the line of slope when graphed

Answer 9

Analytical Bias

Question 10

Reported lab results do not correspond to the correct value

Answer 10

Analytical Bias

Question 11

Problem on Accuracy (Bias) = ____________

Answer 11

Systematic error

Question 12

Refers to laboratory analyses that are subject to imprecision

Answer 12

Random Analytical Variability

Question 13

Problem on Precision (CV) = _____________

Answer 13

Random Error

Question 14

can be systematic or personnel-related

Answer 14

Errors

Question 15

Sources cannot be completely controlled or identified

Answer 15

RANDOM ERRORS

Question 16

Increase the extent of variability of results

Answer 16

RANDOM ERRORS

Question 17

Displace the mean value on one direction (may be up or down), but do NOT affect the overall variability as shown by the SD value

Answer 17

SYSTEMATIC ERRORS

Question 18

decomposition of reagents during storage

Answer 18

Aging phenomena

Question 19

Series of values on the control chart that continue to increase or decrease for at least a period of six (6) consecutive days

Answer 19

TREND

Question 20

Values that distribute themselves on one side of the mean for at least six (6) consecutive days

Answer 20

SHIFT

Question 21

Q.C. procedures performed on a daily basis within individual laboratories

Answer 21

INTRALABORATORY / INTERNAL

Question 22

Monitoring is carried out using:

Answer 22

o Levey – Jennings Chart
o Westgard Multi-rule Chart
o CUSUM Technique

Question 23

Performed on a less frequent basis (e.g. 3x a year) to compare performance b/w or among laboratories

Answer 23

INTERLABORATORY / EXTERNAL

Question 24

graphical representations that display the control observation as a function or time

Answer 24

QUALITY CONTROL CHARTS

Question 25

Control results are plotted on the Y-axis (ordinate) vs time on the X-axis (abscissa)

Answer 25

LEVEY – JENNINGS CHART

Question 26

a control value that goes beyond ±2SD

Answer 26

Outlier

Question 27

 Uses a series of control rules for interpreting data  False rejection is kept low

Answer 27

2. WESTGARD MULTIRULE CHART

Question 28

 Error detection is improved  Analyse samples of the control material by the analytical method to be evaluated (at least 20 days)

Answer 28

WESTGARD MULTIRULE CHART

Question 29

seeks to identify, measure, and eliminate the large gaps of inefficiency in a process

Answer 29

SIX SIGMA

Question 30

Provides a display of the differences b/w the observed values & the expected mean

Answer 30

CUMULATIVE SUM (CUSUM) CHART

Question 31

Used to monitor small shifts in the process mean.

Answer 31

CUMULATIVE SUM (CUSUM) CHART

Question 32

Obtain the CUSUM by adding the difference (value from the mean) to the CUSUM of the previous differences

Answer 32

CUMULATIVE SUM (CUSUM) CHART

Question 33

Under the interpretation od CUSUM chart. If it is a steep slope, it suggests that?

Answer 33

presence of SE (Out of Control)

Question 34

found in clinical Laboratories with microcomputer Q.C. programs

Answer 34

DECISION LIMIT CUSUM

Question 35

Laboratory’s observed mean for material A (Y-axis) compared to the observed mean for material B (X-axis)

Answer 35

YOUDEN PLOT / SCATTER DIAGRAM

Question 36

Information about the nature of the SE can be obtained when two diff. control materials have been analyzed

Answer 36

YOUDEN PLOT / SCATTER DIAGRAM

Question 37

Presents information in an efficient, graphical format

Answer 37

CHECK SHEET

Question 38

Accomplished with a simple listing of items

Answer 38

CHECK SHEET

Question 39

Used to identify factors that have the greatest cumulative effect on the system

Answer 39

PARETO CHART

Question 40

Used to associate multiple possible causes with a single effect

Answer 40

- Ishikawa or Fish bone diagram

Question 41

Pictorial representations of a process

Answer 41

Flow chart

Question 42

- Used in identifying where errors are likely to be found in the system

Answer 42

Flow chart

Question 43

Provides a simple, graphical view of accumulated data, including its dispersion & central tendency

Answer 43

HISTOGRAM

Question 44

Ease of construction

Answer 44

HISTOGRAM