understanding intended and unintended variation andrew wray – june 17, 2013

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Understanding Intended and Unintended Variation

Andrew Wray – June 17, 2013

What are the 4 components of the theory of profound knowledge?

Rate of back surgery

Supply sensitive condition

• Variation is not limited to utilization

• All dimensions of quality have the potential for variability – clinical outcomes, efficiency, etc.

• Also applies at the level of individuals

Dr. Kishore Visvanathan

Understanding Variation

Walter Shewhart

(1891 – 1967)

W. Edwards Deming

(1900 - 1993)

The Pioneers of Understanding Variation

Intended and Unintended Variation

• Intended variation is an important part of effective, patient-centered health care.

• Unintended variation is due to changes introduced into healthcare process that are not purposeful, planned or guided.

• Walter Shewhart focused his work on this unintended variation. He found that reducing unintended variation in a process usually resulted in improved outcomes and lower costs. (Berwick 1991)

Health Care Data Guide, p. 107

a) Describe an example of intended variation in your project.

b) Describe an example of unintended variation in your project.

Table Exercise:

Understanding Variation: the good and bad

• Unintended:– Poor research – Professional uncertainty– Poor knowledge – professional ignorance

• Intended:– Clinical differences among patients– Personal differences among patients

Most work of improvement is focused on unintended variation

If all variation was unintended, it would be easy to stop. What is difficult is reducing unintended variation while keeping intended variation

Unintended Variation

Reducing Unintended Variation

Shifting Performance

Re-discovery?

• Tonsillectomy – 10 fold variability

• Risk of death with surgical treatment – 8 fold variability

Waiting Time for Clinic Visit

20

25

30

35

40

45

50

55

60

Ave

rage

Day

s

Waiting Time for Clinic Visit

20

25

30

35

40

45

50

55

60

Ave

rage

Day

s

Distribution of Wait Times

0

10

20

30

40

50

60

5 15 25 35 45 55 65 75 85 95 105Wait time (days) for Visit

num

ber of

vis

its

Clinic Wait Times > 30 days

0

24

68

10

12

14

16

C F G D A J H K B I L EClinic ID

# of

wai

ts >

30 d

ays

Relationship Between Long Waits and Capacity

0

5

10

15

20

75 95Capacity Used

# w

ait tim

es >

30

day

s

FREQUENCY PLOT PARETO CHART SCATTER PLOT

Health Care Data Guide, p. 65

Tools to Learn from Variation in Data

RUN CHART SHEWHART CHART

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