Statistical Process Control
Objectives
Statistical Process Control:
Measurement and Analysis of Wait
Time Experienced by WIC
Participants Receiving Nutrition
Education Services
Presenters:
.
Apply HC Management Techniques to a
Public Health Agency
„ Voice of Process and Voice of Customer
„ Process Stability and Process Capability
„ Process Shift
„
Debra Thingstad Boe RN, PHN, BA,
MPH Candidate-University of Minnesota
Supervisor
Dakota County Department of Health
William Riley Ph.D.
Associate Dean-School of Public Health
University of Minnesota
Wait time
C a s e lo a d S e r v e d
Annual Caseload
Wait time is an important factor in
customer service satisfaction and
retention of WIC clients
„ Wait time is the most frequently cited
barrier to receiving WIC services and
taking full advantage of program
benefits
„
80000
70000
60000
50000
40000
30000
20000
10000
0
Wait
time is time spent waiting
for service to happen
1999
2000
2001
2002
2003
2004
2005
Year
Statistical Process Control
Process Improvement
Control Chart includes:
A measure of central
tendency (mean)
A measure of variability
(standard deviation)
„
„
±3 SD from the line of
central tendency
Control Charts are used
to:
Assess process stability
„
„
Stable = no special cause
variation
Produces predictable
results
Assess process capability
„
„
First must be stable
Producing desired results =
meets client expectations
Moving Range Chart Nutrition Service Time
6
5
M o v in g R a n g e
in M in u te s
All work is a process
„ All health care/service can be
broken down into processes
„ Analyzing process steps can help
identify opportunities for
improvement
„
„
4
3
2
1
0
120
505
120
605
120
705 20905 21205 21305 21405 21505 21905 22205
1
1
1
1
1
1
1
Date of Service
Moving Range Nutrition Service
UCLmr
LCLmr
MRbar
Upper Control Limit = UCL
Lower Control Limit = LCL
Define limits of normal
process variability
1
Steps to Achieve Performance
Improvement
Tim e of L obby W ait in M inutes
X Chart of Lobby Time December 2005
35
„ Form
30
20
15
10
5
0
5
050
12
5
060
12
5
070
12
5
090
12
5
120
12
12
130
5
12
140
5
1
12
5
50
1
12
5
90
5
220
12
Date of Service
Average Lobby Time
LCLx
Run
UCLx Lobby Time
Xbar Lobby Time
Relationship of Process Performance
with Client Outcomes
XChart for Lobby Wait Time
December and April
Lobby Wait Time in
Minutes
35
30
25
Lobby Wait
Time
(minutes)
20
15
10
Overall
Satisfaction
5
P
15.1
10.9
0.002
45%
54%
0.01
80
60
PostIntervention
42
42
PreIntervention
6
6
6
6
40
00
42
41
41
10
6
6
6
60
40
40
40
05
12
19
05
05
05
12
12
12
14
12
07
05
0
12
05
Process Improvement
Team
„ Create process map
„ Implement PDCA Cycle
„ Set breakthrough goal
„ Process Redesign or Process
Improvement?
25
Date of Service
Xbars of Lobby Wait Times
Xbar
UCLx
LCLx
Conclusions and Implications
Questions?
Process capability can be measured in a
Public Health Agency using SPC.
„ Process performance can be improved
using CQI techniques.
„ Decreasing lobby wait time is associated
with improved client satisfaction.
„
„
SPC can be used in PH to bring the VOP
closer to the VOC.
Thanks to:
Dorothee Aeppli of the Boen Biostatistics Laboratory and
Dakota County Department of Health Staff for project assistance
2
Contact Information:
„
„
Debra Thingstad Boe, RN PHN, BA MPH Candidate
Supervisor-Dakota County Department of Health
14955 Galaxie Avenue
Apple Valley, Minnesota 55124
e-mail deb.boe@co.dakota.mn.us
952-891-7502
Back-up slides
„
Slides available but probably won’t use
William Riley, Ph.D.
Associate Dean
School of Public Health
University of Minnesota
420 Delaware Street SE, MMC 729
Minneapolis, Minnesota 55455
612-625-0615
e-mail riley001@umn.edu
Project Objectives
„
Apply management analysis techniques used
in the healthcare industry to a Public
Health program
Measure the service process experienced by
clients
Statistical
Measure the voice of the customer about
the service provided by the process
„
Consider ways the process can be improved
better
support
„
„
Look for variation outside expected
boundaries
Five tests are used
Meets
minimum and maximum number of runs
Assess for outliers (points falling outside control
limits)
Long runs (7 or more points on the same side of
control line) are absent
Trends (series of consecutive ascending or
descending data points) absent
Zig zag pattern (alternating up and down points)
absent
process control techniques
„
Customer
SPC Tests for Special Cause
satisfaction survey
meet client needs
population health goals
X Chart of Nutrition Education Time
December and April
Process Flowchart
Step 3:
Client waits in lobby
for nutrition staff
Step 4:
Nutrition staff calls
number for client
Greets staff
Go to clinic room
Step 5:
AE Contact between
client and nutrition staff
in clinic room
Step 6:
Return to lobby – leave
lobby
14
Service Time in Minnutes
Step 2:
Client enters lobby
16
12
10
8
6
4
2
0
12
05
05
12
06
05
12
07
05
12
09
05
12
12
05
12
13
05
12
14
05
12
15
05
12
19
05
12
22
05
Step 1:
Client Arrives at Building
•Service starts in the
parking lot
Barriers:
•Take number
and hang up
•Nutrition
education
•SignoDecided
Barriers
receipt
in AE
and
Receptionist
Barriers:
room
collect
activities
it Role
•Enough
parking
on&goal
•Ask for WICbased
folder
verification
info
•Language
line
•Lobby
in
corridor
•Directs
crowded
clients
– no place to
oNotes
from•Distance
previous
contact
from
door
•If ask
about
oTheir
concerns
•Frame
visit
tell
whatclear
doing
oUse
•Client
sit
•CHC
checking
takes
aRole
number
Pre-screener
•How
parking
lot
oCar seats
oAlerts
oCall
•Language
vision
•AskoHealthy
about concerns
•Check
ifdoesn’t
neededspeak
appt in
oSnow –removal
oMA
habits message
•No oReinforce
goal
written
English
•Strollers
or
in
Spanish
oReason
for
visit
(i.e.
pickup,
formula or
future
oManeuvering
strollers
positives
oCHC appt
oF/u
from into
last
visit
- reassessment
•Language
•No
corridor
staff
overseeing
lobby
transfer
DC)
•Verify
ID,
&
through
lot Address
oImmunization
oCheckestablishing
wt, wt
gain,client
prenatal
care
•Difficulty
when
rapport
arrives
Income
•Open
CHIP
folder
•Signage
oDone
if client
asks or note in record
•Set
up (strollers)
next
visit
•Space
•LengthOutreach
ofwhere
time to go
•C&TC
oRead
alerts
•Knowing
•FoodoCircle
packagenext pickup, give AE schedule
•Room
not stocked
oWait
for NS
staff
•WIC
folder
oCheck
nutrition
ed. tab
for goal
oReview
current
package
oStaple
info.
sheet
in
folder
•Room
notchanges
equipped
or
equipment
wait less
broken
•Verify
food
package
oCheck
food
package
oMake
ifoLonger
needed
oAppt
date
time
and
items
to
bringinfo
oEducation
on voucher
use and
changes,
food
•Computer
receptive
to receive
oOpen problems
notes
oComplete
interpreter
request
form
•No available
ID
card past
•Activities
while
waiting
oCheck
voucher
issuance
and cert
Barriers
oEducate
about
extraday,
vouchers
oHighlight
name,
and and
timeplacement of
•Client
prepared
•Cleanliness
•Computer
endnot
dates
food
items
on
vouchers
•Close
visit
•Confusion
about
AE vs. appt
problems
from
lastwhy
apptpresent
requests
•PrintoF/u
vouchers
oCheck
If •No
any pre-screener
additional help is needed
•Printer
problems
oReview
vouchers
-(varies
person
to
person)
•Verify
ID income
&to
address
if noother
pre-screener
oRepeat
when
return
and
key
oPlace in folder
scheduled
oCheckedalerts
oGather
material in plastic sleeve
information
oIf not available educate about verification
items and AE dates
40
30
6
40
40
6
40
50
6
40
60
6
41
00
6
41
10
6
41
20
6
41
40
6
41
70
6
42
00
6
42
40
6
42
60
6
42
70
6
42
80
6
„
Date of Service
Xbar of Nutrition Education Time
Xbar
UCLx
LCLx
3
Xbar of Xbars
UCLx
LCLx
Xbar of Xbars
6
6
20
Long Run
15
10
5
0
Service time in Minutes
LCLmr
X Chart of Lobby Wait Time April 2006
Xbars of Nutrition Education Time
Dates of Service
Moving Range Total Service Time
MRbar
Xbar
UCLmr
UCLx
42
80
60
00
40
10
60
40
6
6
6
6
6
6
6
MRbar
42
42
05
05
Moving Range of Xbar Observations
41
41
40
40
19
Moving Range Chart of Nutrition Education Time
12
LCLx
05
0
14
42
42
42
41
41
40
40
6
6
6
6
6
40
00
60
80
6
60
10
6
40
10
12
15
12
20
12
5
05
0
12 5
07
0
12 5
12
05
12
14
0
12 5
19
05
25
S e r v ic e T im e in
M in u te s
30
05
05
12
35
07
6
5
4
3
2
1
0
S e r v ic e T im e in
M in u te s
Service Time in
Minutes
40
12
05
Date of Service
12
30
40 6
40
40 6
50
40 6
60
41 6
00
41 6
10
41 6
20
41 6
40
41 6
70
42 6
00
42 6
40
42 6
60
42 6
70
42 6
80
6
40
05
12 0 5
06
12 0 5
07
12 0 5
09
12 0 5
12
12 0 5
13
12 0 5
14
12 0 5
15
12 0 5
19
12 0 5
22
05
12
45
40
30
6
40
40
6
40
50
6
40
60
6
41
00
6
41
10
6
41
20
6
41
40
6
41
70
6
42
00
6
42
40
6
42
60
6
42
70
6
42
80
6
Date of Service
80
6
30
40 6
40
40 6
50
40 6
60
41 6
00
41 6
10
41 6
20
41 6
40
41 6
70
42 6
00
42 6
40
42 6
60
42 6
70
42 6
80
6
40
UCLx
42
70
6
UCLmr
42
60
40
MRbar
42
6
6
S e rv ic e T im e in M in u te s
05
12 05
06
12 05
07
12 05
09
12 05
12
12 05
13
12 05
14
12 05
15
12 05
19
12 05
22
05
12
Xbar
42
70
00
6
6
6
Moving Range of Nutrition Education Time
42
40
20
6
6
6
6
6
Xbar Total Service Time
41
41
41
10
00
60
50
40
30
W a it T im e in M in u te s
25
41
41
40
40
40
40
X Chart of Total Service Time
December and April
Moving Range Chart for Lobby Wait Time December 2005
and April 2006
25
20
15
10
5
0
Date of Service
Date of Service
UCLmr
LCLmr
Moving Range Chart for Total Service Time
December 2005 and April 2006
20
15
10
5
0
LCLmr
16
X Chart Nutrition Education April 2006
14
12
10
8
6
4
2
0
Date of Service
LCLx
4
Logistic Regression Analysis
X Chart of Total Service Time April 2006
S e rv ic e T im e in
M in u tes
Overall Satisfaction Rating
35
Overall Satisfaction levels
30
very good, great
unacceptable, dissatisfied, satisfactory,
good
25
73% of all respondents
selected ≥ very good
≥Very Good = 211
≤Good =75
20
Variables used for development of univariate p-values
against overall service satisfaction
15
10
Satisfaction-Lobby Wait
0.0001
5
Satisfaction-Nutrition Service
0.0001
0
Service Initiation-Greeted/ Asked about
questions
0.159
40306 40406 40506 40606 41006 41106 41206 41406 41706 42006 42406 42606 42706 42806
Nutrition Service Transition-told what to expect 0.004
today
Date of Service
Xbar Total Service Time
UCLx
LCLx
Xbar of Xbars
Nutrition Service-Asked if questions
0.217
Expected Lobby Wait Time
0.032
X Chart Tests for Special Cause
Spearman’s Rank Correlations
Satisfaction
Variables
Expected
Service Time
Perceived
Nutrition
Service Time Service
0.371****
Perceived
Time
Lobby
Wait
Total
Service
-0.063
-0.138
-0.119
-0.314**** -0.277****
SatisfactionNutrition
Services
0.683****
SatisfactionLobby Wait
-0.009
0.507****
0.514****
305≤ N≤319- group includes all survey respondents
not all people responded to every question
Number of runs
(Need 3-8)
Lobby
Wait
Time
Nutrition
Education
Total
Service
Time
4
6
4
Long runs
None
None
None
Trend
None
None
None
Zig Zag Pattern
None
None
None
Data points
outside control
limits
No
No
No
****Correlation Significant at p<0.0001
X Chart Tests for Special Cause April
2006
Number of runs
(Need 4-11)
Long runs
Lobby
Wait
Time
Nutrition
Education
Total
Service
Time
6
8
6
Present
None
Present
Trend
None
None
None
Zig Zag Pattern
None
None
None
Data points
outside control
limits
No
No
No
Statistical Process Control
Statistical Process Control (SPC) is a
tool that utilizes statistical parameters
to produce useful information to
understand how a process works over
time.
„ Quantifies how the process is
performing before and after
intervention
„ Can help identify underlying causes
of process issues and approaches
for process improvement
„
5
Project Setting
Moving Range Chart Lobby Wait Time
December 2005
20
15
10
5
5 05
1 20
6 05
120
70 5
1 20
9 05
12 1
2 05
1 21
305
1 21
405
M o v in g R a n g e
in M in u te s
T im e o f N u tr it io n S e r v ic e in
M in u t e s
12 1
50 5
1 21
9 05
1 22
505
120
2 05
LCLmr
MRbar
905
120
205
121
305
1 21
405
121
505
121
905
121
205
122
Date of Service
Moving Range
Mrbar Total Service Time
05
12
22
19
12
15
12
05
05
05
05
12
12
13
14
05
05
90 5
120
205
121
305
121
505
121
405
121
905
121
205
122
LCLx Nutrition Time
Xbar Nutrition Service Time
X Chart of Total Service Time
2
0
705
120
705
120
Average Nutrition Service Time
UCLx Nutrition Service Time
S e r v ic e T im e
in M in u te s
S e rv ic e T im e
in M in u te s
UCLmr
10
8
6
4
605
120
605
1 20
Run
16
14
12
505
1 20
MR bar
Date of Service
Moving Range Chart of
Total Service Time
20
18
LCLmr
16
14
12
10
8
6
4
2
0
Date of Service
Moving Range Nutrition Service
UCLmr
X Chart Nutrition Service Time
6
5
4
3
2
1
0
1 20
12
Date of Service
Moving Range
Moving Range Chart
Nutrition Service Time
12
07
09
12
06
12
05
12
05
05
0
05
M o v in g R a n g e in
M in u te s
25
12
Project was conducted in one
metropolitan county Public Health
Department WIC site
„ County serves the third largest WIC
caseload in Minnesota
„ Site serves over half of the county WIC
participants
„ Project focuses on the Nutrition
Education and Voucher Issuance process
„
45
40
35
30
25
20
15
10
5
0
505
120
605
120
705
1 20
905
1 20
LCLmr
3 05
12 1
405
121
50 5
121
905
121
205
122
Date of Service
Run
UCLmr
2 05
12 1
Average Total Service Time
LCLx
UCLx
Xbar Total Service Time
6
Total Service Time, Nutrition Education Time,
Lobby Wait Time with Averages- December 2005
Actual, Perceived, and Expected Service Time
100%
40
Cumulative Frequency
Percent
90%
Length of Service Time
in Minutes
35
30
25
20
15
10
80%
X bar Lobby
Wait Time
70%
60%
50%
40%
30%
X Bar Total
Service Time
20%
10%
0%
5
0-5
6-10
0
120505
120605
120705
120905
121205
121305
121405
121505
121905
Dates of Service
Lobby Wait Time
Total Service Time
Nutrition Education Time
Average Lobby Wait Time
Average Total Service Time
Average Nutrition Education Time
Spearman’s Rank Correlations
Variables
Actual
Actual Nutrition
Lobby Time Education Time
-0.063
0.289****
0.071
Expected Service
Time
0.343****
0.019
0.336****
Perceived Service
Time
0.500****
-0.040
0.491****
SatisfactionNutrition Service
-0.065
0.008
-0.039
Satisfaction-Lobby
Wait
-0.392****
0.046
-0.364****
Satisfaction-Total
Service
-0.210
0.045
-0.165
>60
Expected Wait Time
Actual Lobby Wait Time
Perceived Total Service Time
Actual Total Service Time
Delivering Service
Actual Total
Service Time
Group Size
11-15 16-20 21-25 26-30 31-45 46-60
Range of Service time
122205
Satisfaction is important when
delivering services rather than
products
„ The product of service delivery is
intangible, so satisfaction centers on
perceptions about performance
„
Experiences
Reactions
****Significant at the p<0.0001
to provider’s behaviors
Timed and Surveyed Group
146 ≤ N ≤ 169
Satisfaction and Quality
„
„
Satisfaction is related to a specific service
encounter
Quality is based on the difference between
service expectations and service performance
Client satisfaction is based on the
extent to which clients perceive
the service to have met, fallen
short or exceeded their
expectations
The Voice/View of the Customer
What do clients/customers want?
Why do they come to WIC?
„ Why do they keep coming to WIC?
„ From the customer view, why is WIC
important (what’s in it for me)?
„ How do we know?
„
„
7