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