Quick Review Cards for Medical Laboratory Science

Interpretation of Quality Control

Datacontinued

TERM EXPLANATION

Outlier

Shift

A control result outside established limits. May be due to chance or may indicate problem in test system. If it

occurs more than once in 20 successive runs, investigation must be carried out.

6 consecutive control values on same side of mean.

2

+ 2 S.D.

+ 1 S.D.

• 1 S.D.


• 2 S.D.

4 6 8 10 12

Day

14 16 18 20

X

Levey-Jennings chart showing outlier. (Modified from Strasinger SK, Di Lorenzo MS. Urinalysis and

Body Fluids, 5th ed. Philadelphia: FA Davis; 2008:133.)

24681012

Day

14 16 18 20

+ 2 S.D.

+ 1 S.D.

• 1 S.D.


• 2 S.D.

X

Levey-Jennings chart showing shift. (From Strasinger SK, Di Lorenzo MS. Urinalysis and Body Fluids,

5th ed. Philadelphia: FA Davis; 2008:133.)

continued...

Laboratory Operations Review 51