Module 3

Question 1

Statistical QC

Answer 1

use of controls and qc charts to monitor analytical methods Known concentrations of analytes

Question 2

Non statistical QC

Answer 2

procedure which maintains and improves performance

Question 3

examples of non statistical QC

Answer 3

produce and monitor high quality water Calibrate lab equipment as schedules monitor temps document maintmance

Question 4

purpose of running controls with patient tests

Answer 4

to detect error int he procedure

Question 5

Properties of controls

Answer 5

Number of analytes: single or multi Concentration of analytes: Different levels Matrix: same physical and chemical matrix as patient samples May be liquid or lyophilized

Question 6

Control range

Answer 6

acceptable range for normal day to day variation

Question 7

how to establish a control range

Answer 7

control sample ran minimum 20 times over 10 days to establish initial range Mean and SD are calculated Distribution is assumed Gaussian; any values outside of +-3SD are excluded and mean and SD are recalculated using remaining data

Question 8

+/- 1S contains about

Answer 8

68% of the values

Question 9

+/- 2S contains about

Answer 9

95% of the values

Question 10

+/- 3S contains about

Answer 10

99% of the values

Question 11

95% confidence interval

Answer 11

+/- 2S range is selected for control range. This means 95% of all control values should fall in this range

Question 12

Levey Jennings Chart

Answer 12

Statistical QC Results on y axis, time on x axis Range should be big enough for +/- 4s

Question 13

Levey jennings chart must be labeled with (7)

Answer 13

Name of test Name, level, lot # of control material Units of measurement Analytical system Mean and SD Time period covered by chart

Question 14

What to do if control value is out of range

Answer 14

plot on chart Circle with red ink Troubleshoot and document Control must be in range in order to release patient results

Question 15

Types of errors

Answer 15

Random: increased scatter, decreased precision Systematic (Shift): error sources that produce consistent effects on values; pos OR neg Systematic (Trend): ex. reagent breaking down

Question 16

*************** Error type: Random Examples of causes

Answer 16

Bubbles or leaks Poor mixing; precipitates in reagents/controls Unstable temp or power supply Poor technique Dirty or damaged probes

Question 17

*************** Error type: Systematic Examples of causes

Answer 17

MOST COMMON: Change in lot # (calibrators, controls, reagents) Improperly prepared solutions Deterioration due to improper storage/handling Less common: Deterioration of instrument components Maintenance overdue Improperly performed maintenance or component replacement Calibration time exceeded/overdue Environmental changes (temp, humidity)

Question 18

False rejection

Answer 18

%5 of control values will fall out of range even if the method is performing properly

Question 19

If using 2 control levels, false rejection rate is

Answer 19

10% Add 5% per extra control level

Question 20

Multi rule QC

Answer 20

approach to minimize change of false rejecting while still maintaining high levels of error detection Ex. Westgard Rules

Question 21

Rule violation within run

Answer 21

a rule violation with a) only one single run of a control level b) within one run of different control levels ran at the same time

Question 22

Rule violation across runs

Answer 22

a rule violation occurring over more than one run of a control level (or levels)

Question 23

Rule violation within controls (control levels)

Answer 23

a rule violation by only one level of control

Question 24

Rule violation across controls

Answer 24

a rule violation including 2 different levels of control

Question 25

1 2s rule

Answer 25

Warning rule Random error Dont reject run One result outside of +/- 2s

Question 26

1 3s rule

Answer 26

RE, reject run One result outside +/- 3s

Question 27

2 2s rule

Answer 27

SE, reject run 2 consecutive results outside +/- 2s Can be across runs or across control levels

Question 28

R 4s rule within run

Answer 28

RE, reject run 4s spread between results occurring ACROSS CONTROL LEVELS

Question 29

R 4s rule across runs, within control level

Answer 29

RE, reject run 4s spread between results

Question 30

4 1s rule one level

Answer 30

SE, reject run 4 consecutive results outside +/- 1s Across runs

Question 31

4 1s Rule Two level

Answer 31

across control levels (2 consecutive on each)

Question 32

10x rule One level

Answer 32

SE, reject run 10 consecutive results on one side of the mean Applies across runs

Question 33

10x rule Two level

Answer 33

across control levels (5 on each)