wow! i didn’t know i could do that with ithink/stella! also known as the ron popeil (aka ronco)...

Wow!I Didn’t Know I Could Do

That with iThink/STELLA!

Also known as the Ron Popeil (aka Ronco) approach:“But wait, there’s more!!”

Chris SoderquistPontifex Consulting

Wow. I didn’t know I could…

• Use an attribute to determine transit time on conveyor

• Use a Weibull distribution to determine product life

• Run goodness of fit tests so easily• Link models to organizational "scorecards"• Create a multiplayer game • Excel forms• Build student models with built-in reports, and...more!

Plus…Q&A. Learn from each other what you can do with the software

Really Geeky stuff

• Attribute to determine transit times

• Weibull distributions• Linking models to external analyses (goodness of fit tests)

• Linking to organizational scorecards

Linking Attributes to Transit Times

Perhaps you want to model…

• Clinic operations, where different treatment types have different expected transit times

or perhaps…

• Logistics where different product types have different shipping times

Using an Attribute to Determine Transit Times

One Approach

• Use 2 chains Track the attributes entering (or average time)

e.g. treatment = physical vs. sick visit; time=30 min vs. 15 min Track people (actual units) in other chain

In Exam

In WaitingRoom

arrivingin waiting room

beingcalled

On Wayto Exam

enteringexam

BecomingNext on

List completing

moving upthe list

~time inexam

stop becausesomeone's in

exam

Patient typePeople Waitingin Waiting Room

counting upentering

peopleentering

leaving

People inExam

∑ Total Peoplein Process

Using an Attribute to Determine Transit Times

One Approach

In this example• Numbers enter (e.g. 5-15) Patient Type = INT(RANDOM(5,15))• If no one In Exam, patient moves right through process to exam (with a DT delay, so you might wish a small DT)• Once someone is In Exam stop the Becoming Next on List conveyor• PULSE from entering exam• Time in exam = entering exam*DT if using time value; • Value for entering exam will determine time in exam can also use a graphical function to relate patient type

In Exam

In WaitingRoom

arrivingin waiting room

beingcalled

On Wayto Exam

enteringexam

BecomingNext on

List completing

moving upthe list

~time inexam

stop becausesomeone's in

exam

Patient typePeople Waitingin Waiting Room

counting upentering

peopleentering

leaving

People inExam

∑ Total Peoplein Process

Weibull Survival Times

Say you want to model how long a product will last in the installed base…

The Weibull distribution works well for product survivability

mean time till failure; k=shape

Tech doc shows the equation for generating Weibull random numbers

Need a stock to hold units before stamping survival times onto it

Small DT is essential to get individual units

PULSE units onto conveyor to stamp failing

later IB

lambdaor mean time

to failure

Shape

RecentSales

SalesInstalled

Base

settingsurvival forrecent sales

selling

TotalFailed

Recent IB

ExpectedLifespan sales

Weibull Survival Times becomes challenging when there is initial stuff in system

• Sometimes you may start off a model with stuff already “in process”

• Because you need to stamp products to assign Weibull survival times, you can have an initial stock with everything in it and then quickly PULSE everything (1 at a time) onto the conveyor

• This “stamps” the survival time onto the unit

ExpectedLifespanInitial IB

Shapelambda

or mean timeto failure

UnassignedFailure Times

InitialInstalled

Base

setting survivalfor initial

Installed Base

failinginitial IB

TotalFailed

Initial IB

CT

Use Excel to calculate Thiel Statistics for Goodness of Fit

• Export model output to Excel

• Include real world series plus model series

• Thiel statistic calculates % of error attributable to Bias Unequal variation Unequal covariation

MonthsSubscribers model

Subscribers actual

Sq Error F/100 APE

Jan 50 50 0.000 0.00%Feb 60 56 18.404 7.66%Mar 73 74 1.664 1.74%Apr 88 84 13.542 4.38%May 106 109 10.693 3.00%Jun 128 123 20.250 3.66%July 154 147 45.563 4.59%Aug 185 192 43.560 3.44%Sep 224 211 158.256 5.96%Oct 270 279 88.172 3.37%Nov 325 347 478.734 6.31%Dec 392 383 81.903 2.36%Dec: Final 473 467 33.293 1.24%

MSE 82.836UM 0.001472US 0.009783UC 0.988745MAPE 3.98%

Goodness of Fit Tests (including Thiel statistic)

0

50

100

150

200

250

300

350

400

450

500

Jan Feb Mar Apr May Jun July Aug Sep Oct Nov Dec

Model forecast

Actual

*In isee systems sample model

Software features that support building scorecards and strategy

maps

Modeling features• Converters (to start)• Sector frames• Stock/flow maps• Generic templates keep it

operational (see appendix)

• Feedback loops improve Interface features• Numeric displays• Warning flashers• Sliders, knobs (other

input devices for testing strategies)

• Linking to Excel allows access to pie charts and other interesting dashboard output

Customer

Projects

Customers

generating

projects\customer

Staff

leaving

attrition %

Cash

revenue

completingavg project fee

Generic templates

0

0.0%

0.0%

0.00.0

0.00.0

0.0

Linking to Excel (and dashboard tools) can facilitate course

corrections

Real DashboardDynamic Strategy Dashboard

Mental Model

Mental Model

*made in iDashboard which links to Excel files

*

Fun Experiences

• Multiplayer sims Including Spreadsheet interfaces

• Student reports

Multiplayer Simulations

• Link up several control panels to one model

• Players/Teams can assume different roles in a system

• Easily done with iThink/STELLA and Excel in 9.1

Assumptions Assumptions

Assumptions

Assumptions

Assumptions Assumptions

Model


How it’s done Pt.1

• Develop the model• Any arrayed variable inputs need

to be pulled out (e.g. orders[A,B] becomes orders A and orders B)

Inventoryselling

demand

Orders inPipeline

receivingordering

time delay

orders

orders A orders B • Create tables for each role--I usually put them all in 1 pad and create a page for each role

• You may need to duplicate variables



=INDEX('Table from model'!2:2,MATCH(9.99999999999E+307,'Table from model'!2:2))

Use a special equation on control panel to report the last value in a row. e.g. Variable for A’s inventory will be in row 2 in iThink

table, so following Index equation says 2:2

Create a Save button which will update the iThink model

Create a Link from the input fields to another sheet. I put

them in vertically

Create a Link from the input fields to 3rd sheet which will take date from

iThink/STELLA



Import from the Import sheet. Choose dynamic.

Export to the XLS sheet set up to take the table. Choose dynamic.



• In the input sheets, have the teams make decisions

• Then press Submit decisions to save

• This updates the iThink model• Run the model for the chosen period (I use a Simulate button to make it easy to see)

Student Reports

• Suppose you want students (or even teams of executive education participants) to hand in reports that show how they progressed through a learning lab

• You can create interactive student reports that allow you to get data on simulation runs, notes taken, questions answered, and more

• You can even set it up so that students cannot get some challenges/questions until they have solved simpler challenges

Set up

Main Menu Experiments Student Notebook

Switch a variable in the model on when navigating to this experiment to turn on a feedback loop

Don’t want student to enter Experiment 2 until after they’ve done Experiment 1. Choose password protect in navigation dialog.

Select Print Exports in graph so it will be sent to printer

Select Print Exports in text box so it will be sent to printer

Contact Info

Chris SoderquistPontifex Consulting11 Sargent StreetHanover, NH 03755(603) 653-0228

[email protected]

wow! i didn’t know i could do that with ithink/stella! also known as the ron popeil (aka ronco)...

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