8/8/2019 WestgardRules

1/3

Traditional "Westgard Rules"

Control

Data

In-Control

R eport Data

Out-of-Control, R eject Analytical Run

12sone point out

of 2 S D

13sone point

outside 3 S D

22s(across runs)

2 C O N S E C U T IV E

values outside thesame 2 SD

or

(within run)

2 C O N S E C U T IV E

values outside the

SAME 2 SD.

R 4sThe range

(difference) between

two controls within arun exceeds 4 S D s.

This rule is only to be

used within a run, not

across runs.

41s4 C O N S E C U T IV Econtrol values on

one side of the

mean and furtherthan 1S D from

the mean.

This can be withinone control across4 consecutive runs

orwithin 2 controls

across 2consecutive runs.

Problem:

Resolution:

Ye s

No

No No No N

Ye s

Ye s

Ye s

Ye s

Find out more

8/8/2019 WestgardRules

2/3

Mode

rn"WestgardRu

les":N'sof2an

d4

Control

Data

In-Control

ReportData

Out-of-Control,RejectAnalyticalRun

13s

onepoint

outside

3SD

2

2s

(acrossruns)

2CONS

ECUTIVE

valueso

utsidethe

same2SD

or

(with

inrun)

2CONS

ECUTIVE

valueso

utsidethe

SAME2SD.

R4s

T

herange

(differe

nce)between

twoco

ntrolswithina

runex

ceeds4SDs.

Thisru

leisonlytobe

usedw

ithinarun,not

ac

rossruns.

41s

4C

ONSECUTIVE

controlvalueson

onesideofthe

me

anandfurther

th

an1SDfrom

themean.

Thiscanbewithin

one

controlacross

4co

nsecutiveruns

or

within2controls

across2

con

secutiveruns.

10x

1

0CONSECUTIVE

valuesonONE

sideofthemean.

Thiscanbewithin

onecontrolacross

10consecutiveruns

or

within2controls

across5

consecutiveruns.

Problem:

Resolution:

No

No

No

No

No

Yes

Yes

Ye

s

Yes

Yes

Date:

Tech:

F

indoutmoreathttp://www.westgard.com

8/8/2019 WestgardRules

3/3

Mode

rn"WestgardRu

les":N'sof3an

d6

Control

Data

In-Control

ReportData

Out-of-Control,RejectAnalyticalRun

13s

onepoint

outside

3SD

2of32s

(acrossruns)

2outofthelast3

valueso

utsidethe

same2SD

or

(with

inrun)

2outofthelast3

valueso

utsidethe

SAME2SD.

R4s

T

herange

(differe

nce)between

twoco

ntrolswithina

runex

ceeds4SDs.

Thisru

leisonlytobe

usedw

ithinarun,not

ac

rossruns.

31s

3C

ONSECUTIVE

controlvalueson

onesideofthe

me

anandfurther

th

an1SDfrom

themean.

Thiscanbewithin

one

controlacross

3consecutiveruns

or

within3controls

across1

consecutiverun.

12x

1

2CONSECUTIVE

valuesonONE

sideofthemean.

Thiscanbewithin

onecontrolacross

1

2consecutiveruns

or

within3controls

across4

co

nsecutiveruns,etc.

Problem:

Resolution:

No

No

No

No

No

Yes

Yes

Ye

s

Yes

Yes

Date:

Tech

:

F

indoutmoreathttp://www.westgard.com