duncan miller mbchb frca · variation and basic queue theory . topics • variation • basics of...
Post on 29-Oct-2019
1 Views
Preview:
TRANSCRIPT
Duncan Miller MBChB FRCA
Anaesthesia Registrar
Former QI fellow
Variation and Basic Queue Theory
Topics
• Variation
• Basics of queue theory
• Practical examples
• Gantt Charts
• Other Variation Concepts
Variation
Duncan Miller
Duncstable
Dunc
‘Intended Variation’
Daniel
Intended
and
Unintended Variation
Sir Ronald
Fisher
(1890 - 1962)
William Sealy
Gosset
(1876 - 1937)
Walter
Shewhart
(1891 – 1967)
W. Edwards
Deming
(1900 - 1993)
Common Cause Variation
Shewhart’s Theory of Variation
• Common Causes—those causes inherent in the system over time, affect everyone working in the system, and affect all outcomes of the system
•Chance cause
•Stable process
Common Cause Variation
Shewhart’s Theory of Variation
• Special Causes—those causes not part of the system all the time or do not affect everyone, but arise because of specific circumstances
• Assignable cause
• Unstable process
0
20
40
60
80
100
120
Consecutive trips
Min.
Special Cause - My trip to work
Mean
Upper process limit
Lower process limit
RULE 1 – THE OUTLIER
Point above Upper Control Limit (UCL)
MEAN
LCL
UCL
Or point below Lower Control Limit (LCL)
RULE 1 – THE OUTLIER
MEAN
LCL
UCL
MEAN
Eight points above centre line
RULE 2 – THE SHIFT
LCL
UCL
MEAN
RULE 2 – THE SHIFT
LCL
UCL Or eight points below centre line
MEAN
Six points in a downward direction
RULE 3 – THE TREND
LCL
UCL
MEAN
RULE 3 – THE TREND
LCL
Or six points in an upward direction
UCL
Considerably less than 2/3 of all the points fall in this zone
LCL
UCL
RULE 4 – ALL ON THE EDGE
MEAN
RULE 4 – ALL IN THE MIDDLE
Or considerably more than 2/3 of all the points fall in this zone
MEAN
UCL
LCL
Variation – what to do?
21
Common Cause
Variation
Reduce variation: Increase precision -
make the process even more reliable.
Not satisfied with performance
(average): Redesign process to get a better result.
Special Cause
Variation
Root cause analysis: If Desirable: Maximise, optimise, replicate,
standardise.
If Undesirable: Minimise, eliminate.
22
Responding to Variation
Variation and Queues
“If I had to reduce my message for management to just a few words, I’d say it all had to do with reducing variation.” W. Edwards Deming
Variation & Queues
Consecutive Patients
Pro
cedure
Tim
e (
Min
ute
s)
50%
100% 80%
80% rule is the most efficient balancing waiting and waste
Erlangs rule of thumb
Jan 1878 - Feb 1929
Calculating the 80% rule
80% Rule = Variation x 0.8 + Lowest Value
(Variation = High Value – Low Value)
•Variation = 23 – 7 = 16
•16 x 0.8 = 12.8
•12.8 + 7 (Low value) = 19.8
•19.8 (approx. 20min)
Plan Cycle Time = 20m
Role Cycle Time at
80%
Lung Function 15m
Weight & Nurse 10m
Dietician 20m
Dr 20m
Others 15m
Cycle time at 80% - PDSA 1 M
ore
Variable
More
Relia
ble
1.15 1.30 2.00 2.30 3.00 3.30 4.00 4.30 5.00
Patient 1L L L W N D D D D Dr Dr Dr Dr O O O
Patient 2L L L W N D D D D Dr Dr Dr Dr O O O
Patient 3L L L W N D D D D Dr Dr Dr Dr O O O
Patient 4L L L W N D D D D Dr Dr Dr Dr O O O
Patient 5L L L W N D D D D Dr Dr Dr Dr O O O
Patient 6L L L W N D D D D Dr Dr Dr Dr O O O
Patient 7L L L W N D D D D Dr Dr Dr Dr O O O
Patient 8L L L W N D D D D Dr Dr Dr Dr O O O
Patient 9L L L W N D D D D Dr Dr Dr Dr O O O
Patient 10L L L W N D D D D Dr Dr Dr Dr O O O
Patient 11L L L W N D D D D Dr Dr Dr Dr O O O
Patient 12L L L W N D D D D Dr Dr Dr Dr O O O
Patient 13L L L W N D D D D Dr Dr Dr Dr O O O
Patient 14L L L W N D D D D Dr Dr Dr Dr O O O
Patient 15L L L W N D D D D Dr Dr Dr Dr O O O
Patient 16L L L W N D D D D Dr Dr Dr Dr O O O
Patient 17L L L W N D D D D Dr Dr Dr Dr O O O
Patient 18L L L W N D D D D Dr Dr Dr Dr O O O
1.15 1.30 2.00 2.30 3.00 3.30 4.00 4.30 5.00
Patient 1L L L W N D D D D Dr Dr Dr Dr O O O
Patient 2L L L W N D D D D Dr Dr Dr Dr O O O
Patient 3L L L W N D D D D Dr Dr Dr Dr O O O
Patient 4L L L W N D D D D Dr Dr Dr Dr O O O
Patient 5L L L W N D D D D Dr Dr Dr Dr O O O
Patient 6L L L W N D D D D Dr Dr Dr Dr O O O
Patient 7L L L W N D D D D Dr Dr Dr Dr O O O
Patient 8L L L W N D D D D Dr Dr Dr Dr O O O
Patient 9L L L W N D D D D Dr Dr Dr Dr O O O
Patient 10L L L W N D D D D Dr Dr Dr Dr O O O
Patient 11L L L W N D D D D Dr Dr Dr Dr O O O
Patient 12L L L W N D D D D Dr Dr Dr Dr O O O
Patient 13L L L W N D D D D Dr Dr Dr Dr O O O
Patient 14L L L W N D D D D Dr Dr Dr Dr O O O
Patient 15L L L W N D D D D Dr Dr Dr Dr O O O
Patient 16L L L W N D D D D Dr Dr Dr Dr O O O
Patient 17L L L W N D D D D Dr Dr Dr Dr O O O
Patient 18L L L W N D D D D Dr Dr Dr Dr O O O
1.15 1.30 2.00 2.30 3.00 3.30 4.00 4.30 5.00
Patient 1L L L W N D D D D Dr Dr Dr Dr O O O
Patient 2L L L W N D D D D Dr Dr Dr Dr O O O
Patient 3L L L W N D D D D Dr Dr Dr Dr O O O
Patient 4L L L W N D D D D Dr Dr Dr Dr O O O
Patient 5L L L W N D D D D Dr Dr Dr Dr O O O
Patient 6L L L W N D D D D Dr Dr Dr Dr O O O
Patient 7L L L W N D D D D Dr Dr Dr Dr O O O
Patient 8L L L W N D D D D Dr Dr Dr Dr O O O
Patient 9L L L W N D D D D Dr Dr Dr Dr O O O
Patient 10L L L W N D D D D Dr Dr Dr Dr O O O
Patient 11L L L W N D D D D Dr Dr Dr Dr O O O
Patient 12L L L W N D D D D Dr Dr Dr Dr O O O
Patient 13L L L W N D D D D Dr Dr Dr Dr O O O
Patient 14L L L W N D D D D Dr Dr Dr Dr O O O
Patient 15L L L W N D D D D Dr Dr Dr Dr O O O
Patient 16L L L W N D D D D Dr Dr Dr Dr O O O
Patient 17L L L W N D D D D Dr Dr Dr Dr O O O
Patient 18L L L W N D D D D Dr Dr Dr Dr O O O
1.15 1.30 2.00 2.30 3.00 3.30 4.00 4.30 5.00
Patient 1L L L W N D D D D Dr Dr Dr Dr O O O
Patient 2L L L W N D D D D Dr Dr Dr Dr O O O
Patient 3L L L W N D D D D Dr Dr Dr Dr O O O
Patient 4L L L W N D D D D Dr Dr Dr Dr O O O
Patient 5L L L W N D D D D Dr Dr Dr Dr O O O
Patient 6L L L W N D D D D Dr Dr Dr Dr O O O
Patient 7L L L W N D D D D Dr Dr Dr Dr O O O
Patient 8L L L W N D D D D Dr Dr Dr Dr O O O
Patient 9L L L W N D D D D Dr Dr Dr Dr O O O
Patient 10L L L W N D D D D Dr Dr Dr Dr O O O
Patient 11L L L W N D D D D Dr Dr Dr Dr O O O
Patient 12L L L W N D D D D Dr Dr Dr Dr O O O
Patient 13L L L W N D D D D Dr Dr Dr Dr O O O
Patient 14L L L W N D D D D Dr Dr Dr Dr O O O
Patient 15L L L W N D D D D Dr Dr Dr Dr O O O
Patient 16L L L W N D D D D Dr Dr Dr Dr O O O
Patient 17L L L W N D D D D Dr Dr Dr Dr O O O
Patient 18L L L W N D D D D Dr Dr Dr Dr O O O
PDSA - Plan
PDSA - Plan
1.15 1.30 2.00 2.30 3.00 3.30 4.00 4.30 5.00
Patient 1L L L W N D D D D Dr Dr Dr Dr O O O
Patient 2L L L W N D D D D Dr Dr Dr Dr O O O
Patient 3L L L W N D D D D Dr Dr Dr Dr O O O
Patient 4L L L W N D D D D Dr Dr Dr Dr O O O
Patient 5L L L W N D D D D Dr Dr Dr Dr O O O
Patient 6L L L W N D D D D Dr Dr Dr Dr O O O
Patient 7L L L W N D D D D Dr Dr Dr Dr O O O
Patient 8L L L W N D D D D Dr Dr Dr Dr O O O
Patient 9L L L W N D D D D Dr Dr Dr Dr O O O
Patient 10L L L W N D D D D Dr Dr Dr Dr O O O
Patient 11L L L W N D D D D Dr Dr Dr Dr O O O
Patient 12L L L W N D D D D Dr Dr Dr Dr O O O
Patient 13L L L W N D D D D Dr Dr Dr Dr O O O
Patient 14L L L W N D D D D Dr Dr Dr Dr O O O
Patient 15L L L W N D D D D Dr Dr Dr Dr O O O
Patient 16L L L W N D D D D Dr Dr Dr Dr O O O
Patient 17L L L W N D D D D Dr Dr Dr Dr O O O
Patient 18L L L W N D D D D Dr Dr Dr Dr O O O
PDSA – Do & Study
Demand is increasing....
More slots needed...
80% = 21mins
3hrs = 8 Patients
80% = 21mins
3hrs = 8 Patients
80% = 18mins
3hrs = 10 Patients
80% = 21mins
3hrs = 8 Patients
80% = 18mins
3hrs = 10 Patients
80% = 14mins
3hrs = 12 Patients
HOW DO YOU REDUCE
COMMON CAUSE VARIATION?
GSM
More Queuing....
Capacity required = 27
Capacity required = 27
Capacity required = 49
(5 beds less than separate units ~£400,000)
46
5 15 35 150 500 1500
Dunbar’s Number
The maximum number of meaningful relationships a person can maintain
Lung Cancer Clinic
47
13 + 11 = 24
Lung Cancer - pooled
And Finally - More Queuing....
Which is best?
C Q
C Q
C Q
S
S
S
C Q
S
S
S
C Q C Q
And Finally - Which is best?
C Q
Long
C Q
Short
S
S
C Q
Long
S
S
S
C Q
Short
C Q
Long
DISCUSSION
THANKS!
top related