Statistics and QC part 3

Question 1

What is the multi-rule system that uses decision criteria rules to determine acceptability of results? This system evaluates more than one level of control pool simultaneously.

Answer 1

Westgard Multi1-Rules

Question 2

1-2s

Answer 2

One control observation exceeds the mean + 2 SD or - 2SD

Question 3

Is 1-2s error considered cause for run rejection?

Answer 3

NO! This is the only one

Question 4

What error may be present in the 1-2s test system?

Answer 4

random or systematic

Question 5

1-3s

Answer 5

One control observation exceeds the mean +3SD or -3SD

Question 6

What error may be present in the 1-3s test system?

Answer 6

random or possibly the beginning of a large systematic error

Question 7

2-2s

Answer 7

Two consecutivve controls exceed the mean + 2SD or two consecutive controls exceed the mean -2SD. These violations must be consecutive and must be on the same side of the mean

Question 8

What error may be present in the 2-2s test system?

Answer 8

systematic error only

Question 9

What are the two applications to the 2-2s rule?

Answer 9

within-run and across runs

Question 10

This application to 2-2s rule affects all control results obtained for the current analytic run. For example if normal (Level 1) and abnormal (Level 2) control are assayed in this run and both levels of control are greater than 2s on the same side of the mean, this run violates with ________ application for systematic error

Answer 10

within-run

Question 11

If Level 1 is -1s and Level 2 is +2.5s, the level 2 result from the previous run must be examined. If level 2 in previous run was at +2s or greater, the ______ application ro systematic error is violated.

Answer 11

across run

Question 12

For 2-2s, violation of the within-run application indicates that ________ error is present and that it affects potentially _____ of the analytical curve

Answer 12

systematic; ALL

Question 13

For 2-2s, violation of the across run application indicates that only a _______ portion of the analytical curve is affected by the error

Answer 13

single

Question 14

R-4s

Answer 14

The difference between two consecutive controls is greater than 4SD. This indicates that two consecutive controls have assayed in opposite directions of each other

Question 15

Example: One control greater than the mean +2SD and the next control greater than the mean -2SD, with the difference between the two greater than 4SD

Answer 15

R-4s

Question 16

What error may be present in the R-4s test system?

Answer 16

identifies with random error only and is applied only within the current run

Question 17

4-1s

Answer 17

Four consecutive controls exceed the mean + 1SD or four controls exceed the mean - 1SD

Question 18

What error may be present in the 4-1s test system?

Answer 18

typically identifies small systematic error or analytical bias

Question 19

How can you eliminate systematic error or analytical bias in 4-1s?

Answer 19

Can be eliminated by performing calibration or instrument maintenance

Question 20

10x

Answer 20

ten consecutive controls exceed the mean on the positive side or ten consecutive controls exceed the mean on the negative side

Question 21

Which rules (5) are not tested unless the 1-2s rule is flagged?

Answer 21

1-3s,2-2s, R-4s, 4-1s, 10x