MIDTERMS: L1 - QC AND QA

Question 1

Laboratory’s best estimate of the analyte’s true value for a specific level of control.

Answer 1

MEAN

Question 2

Quantifies how close numerical values are in relation to each other.

Answer 2

STANDARD DEVIATION

Note: SD is used to set up limits

Question 3

MOTF
1 . Low SD - implies that the data values are spread out over a large range of values
2. High SD - implies that the data values/points are very close to the mean

Answer 3

Both False

High SD - implies that the data values are spread out over a large range of values

Low SD - implies that the data values/points are very close to the mean

Question 4

Described as a graph of all the quality control results in a month

Answer 4

LEVEY JENNINGS CHART

Note: minimum of 20 controls

Question 5

A measure of variability

Answer 5

Coefficient of Variation

Question 6

Useful for comparison

of precision for two different methods or instruments

Answer 6

Coefficient of variation

Question 7

It can also be used as a part of the Internal Quality Control system when performing patients precision testing

Answer 7

Coefficient of variation

Note: The lower the CV, the better

Question 8

MOTF
SDI (Standard Deviation Index)
1. A statistic that measures your lab’s bias relative to your consensus group.
2. It is an estimate of reliability
3. SDI is useful in testing accuracy of a method

Answer 8

All are True

Question 9

SDI (Standard Deviation Index)

interpretation of results:

Answer 9

0 - Ideal score; identical to your peer group

(+/-) 1 to 1.5 - Acceptable to marginal performance; may need to investigate test system bias

(+/-) 1.5 to 2.0 - Marginal performance; may need to perform corrective action

Question 10

A statistic that compares your lab’s precision to that of other labs in a consensus group

Answer 10

CRV (Coefficient of Variation Ratio)

Note: Consensus group is still present but in this case, for your CVR, the inter-laboratory group CV is used not the reference method

Question 11

CRV (Coefficient of Variation Ratio) results and interpretation:

Answer 11

Less than 1 - Acceptable performance; indicates that precision is better than the peer group

1 to 1.5 - Acceptable to marginal performance; may need to investigate test system imprecision

1.5 to 2.0 - Marginal performance; may need to perform corrective action

Question 12

MOTF
1. Shift - defined as abrupt changes in the control values
2. Shifts in QC data represent a sudden and dramatic
positive or negative charge in test system performance
3. 4 or more consecutive results fall on one side of the mean means there is a shift

Answer 12

1,2- true
3 - false

3 - must be 6 or more = REJECT

Question 13

• Indicates a gradual loss of reliability in the test system (6 values)
• Usually subtle

Answer 13

Trent

Question 14

MOTF
1. Systematic Error - a trend or shift away from the laboratory mean
2. Systematic Error - can still be acceptable
3. Random error - any random deviation away from the laboratory
mean
4. Reject if the data value that shows the random
error exceeds ± 2SD

Answer 14

Only 2 is incorrect

2 - not acceptable

Question 15

T or F
One control - values are said to be in control if they fall
within the ± 2SD

Answer 15

True

Question 16

A “multi-rule” system developed by Dr. James O. Westgard based on statistical concepts

Answer 16

Westgard Multirule System

Question 17

MOTF
Westgard Multirule System
1. Use 1-2 or more controls
2. a combination of decision criteria or rules to assess if a system is in-control

Answer 17

1 false, 2 true

1 - need atleast 2 levels of control

Question 18

When a single control observation is outside the ± 2s limits.

Answer 18

12s rule

Question 19

12s rule

1. Not a reason for rejection
2. Warning rule

Answer 19

Both true

Question 20

MOTF
22s rule
1. Violation indicates random error that occurs outside the +/- 2SD
2. Two consecutive controls exceed the mean by +/- 2SD

Answer 20

1 false, 2 true

1 - systematic error

Question 21

41s Rule
- 4 consecutive controls on one side of the mean exceeds
+/-1SD
- Systematic error

Answer 21

True

Question 22

10 consecutive controls on one side of the mean, systematic error

Answer 22

10x rule

Question 23

There is only one data value that occurs outside the ± 3SD, random error

Answer 23

13s rule

Question 24

f there is at least a 4s difference between control values within a single run, the rule is violate for random error

Answer 24

R4s Rule

Question 25

MOTF

1. BIAS/SDI RESULTS ACCURACY /RELIABILITY ARE AFFECTED - very far values from each other
2. PRECISION/REPEATABILITY/CV/ CVI ARE AFFECTED - fall only on one side of the mean

Answer 25

Both false