earned schedule 19_earned schedule_walt lip… · • schedule variance: sv(t) = es – at •...

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International Metrics Congress2007

Earned Schedule …an emerging enhancement to EVM

Walt Lipkebrought to you by the PMI MetSIG and Cheetah Learning

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Brought To You By

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Objective

• Introduce the Earned Schedule Concept

• Develop the Schedule Indicators

• Apply to Project Duration Prediction

• Apply to Schedule Analysis

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Earned Value Basics

Time

$$

PVEVSPI

ACEVCPI

BACPV

AC

EV

SV

CV

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EVM Schedule Indicators

• SV & SPI behave erratically for projects behind schedule

– SPI improves and equals 1.00 at end of project

– SV improves and concludes at $0 variance

• Schedule indicators lose predictive ability over the last thirdof the project

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EVM Schedule Indicators

• Why does this happen?

– SV = EV – PV

– SPI = EV / PV

• At planned completion PV = BAC

• At actual completion EV = BAC

• When actual > planned completion

– SV = BAC – BAC = $000

– SPI = BAC / BAC = 1.00

Regardless of lateness !!

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Earned Schedule Concept

The cumulative value of ES isfound by using EV to identifyin which increment of PV thecost value occurs.

7 months gone by, but the project only has “Earned Schedule” to Month 5Which SV “Answers the mail?” $ behind or 2 months behind schedule?

$

5

Σ PV

Σ EV

Time Now

71 2 3 4 6 8 9 10

A

B

SVc

SVtES

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Earned Schedule Metric

• Required measures

– Performance Measurement Baseline (PMB) – thetime phased planned values (PV) from project start tocompletion

– Earned Value (EV) – the planned value which hasbeen “earned”

– Actual Time (AT) - the actual time duration from theproject beginning to the time at which project status isassessed

• All measures available from EVM

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Earned Schedule Calculation

• ES (cumulative) is the:

Number of completed PV time increments EV exceeds +the fraction of the incomplete PV increment

• ES = C + I where:

C = number of time increments for EV PV

I = (EV – PVC) / (PVC+1 – PVC)

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Interpolation Calculation

$$

I /1 mo = p / q

I = (p / q) 1 mo

p = EV – PVC

q = PVC+1 – PVC

I = 1moEV – PVC

PVC+1 – PVC

PVC+1

ES(calc)

EV

PVC

ES

JulyJuneMay

1 mo

I

p

q

Time

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Earned Schedule Indicators

• Schedule Variance:

SV(t) = ES – AT

• Schedule Performance Index:

SPI(t) = ES / AT

where AT is “Actual Time” – the duration from start to time now

• SV(t) and SPI(t) are time-based (months, weeks …)

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Earned Schedule Indicators

• What happens to the ES indicators, SV(t) & SPI(t), when theplanned project duration (PD) is exceeded (PV = BAC)?

They Still Work …Correctly!!• ES will be PD, while AT > PD

– SV(t) will be negative (time behind schedule)

– SPI(t) will be < 1.00

Reliable Values from Start to Finish !!

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Schedule Variance Comparison

-400

-300

-200

-100

0

J F M A M J J A S O N D J F M

-3

-2

-1

0

0

20

40

60

80

100

J F M A M J J A S O N D J F M0

0.2

0.4

0.6

0.8

1

SV($) SV(t)

Early Finish Project

Late Finish Project

$ Mo

$ Mo

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Schedule Index Comparison

0.98

1.00

1.02

1.04

1.06

1.08

1.10

1.12


0.70

0.80

0.90

1.00

1.10

1.20

1.30


SPI($) SPI(t)

Early Finish Project

Late Finish Project

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Commercial IT Infrastructure Expansion Project Phase 1

Cost and Schedule Variancesat Project Projection: Week Starting 15th July xx

-160

-140

-120

-100

-80

-60

-40

-20

0

20

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

Elapsed Weeks

Do

lla

rs(,

00

0)

-16

-14

-12

-10

-8

-6

-4

-2

0

2

We

ek

s

CV cum SV cum Target SV & CV SV (t) cum

Stop wk 19

Re-start wk 26Sched wk 20

Late Finish Project

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Earned Schedule – Key Points

• ES Indicators constructed to behave in an analogousmanner to the EVM Cost Indicators, CV and CPI

• SV(t) and SPI(t)

– Not constrained by PV calculation reference

– Provide duration based measures of scheduleperformance

– Valid for entire project, including early and late finish

• Facilitates integrated Cost/Schedule project management

(using EVM with ES)

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Schedule Prediction

• Can the project be completed as planned?– TSPI = Plan Remaining / Time Remaining

= (PD – ES) / (PD – AT)where PD is the planned duration (time at BAC)

(PD – ES) = PDWRPDWR = Planned Duration for Work Remaining

• …completed as estimated?– TSPI = (PD – ES) / (ED – AT)

where ED = Estimated Duration

Not Achievable 1.10

Achievable 1.00

Predicted OutcomeTSPI Value

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Schedule Forecasting

• Long time goal of EVM …Prediction of total project durationfrom present schedule status

• Independent Estimate at Completion (time)

– IEAC(t) = PD / SPI(t)

– IEAC(t) = AT + (PD – ES) / PF(t)

where PF(t) is the Performance Factor (time)

– Analogous to IEAC used to predict final cost

• Independent Estimated Completion Date (IECD)

– IECD = Start Date + IEAC(t)

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Earned Schedule Terminology

at Completion (time)

Independent Estimate

Performance Index

To Complete Schedule

Schedule PerformanceIndex

Schedule Variance

Actual Time

Earned Schedule

IEAC(t) = AT + (PD– ES) / PF

IEAC(t) = PD / SPI(t)IEAC(t)Predictors

TSPI(t) = (PD – ES) / (ED – AT)

TSPI(t) = (PD – ES) / (PD – AT)TSPI(t)

SPI(t) = ES / ATSPI(t)Indicators

SV(t) = ES - ATSV(t)

AT = number of periods executedATcum

ES = C + I number of completeperiods (C) plus an incompleteportion (I)

EScumMetrics

at Completion (time)

Independent Estimate

Performance Index

To Complete Schedule

Schedule PerformanceIndex

Schedule Variance

Actual Time

Earned Schedule

IEAC(t) = AT + (PD– ES) / PF(t)

IEAC(t) = PD / SPI(t)IEAC(t)Predictors

TSPI(t) = (PD – ES) / (ED – AT)

TSPI(t) = (PD – ES) / (PD – AT)TSPI

SPI(t) = ES / ATSPI(t)Indicators

SV(t) = ES - ATSV(t)

AT = number of periods executedATcum

ES = C + I number of completeperiods (C) plus an incompleteportion (I)

EScumMetrics

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Independent Confirmation

• SPI(t) & SV(t) do portray the real schedule performance

• At early & middle project stages pre-ES & ES forecasts ofproject duration produce similar results

• At late project stage ES forecasts outperform all pre-ESforecasts

• The use of the SPI(t) in conjunction with the TSPI(t) hasbeen demonstrated to be useful for managing the schedule

Stephan Vandevoorde – Fabricom Airport Systems, Belgium

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Schedule Analysis with EVM?

• Most practitioners analyze schedule from the bottom upusing the network schedule, independent from EVM

….“It is the only way possible.”

– Analysis of the Schedule is overwhelming

– Critical Path is used to shorten analysis

(CP is longest path of the schedule)

• Duration prediction using Earned Schedule provides amacro-method similar to the method for estimating Cost

– A significant advance in practice

• But, there’s more that ES facilitates ….

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Facilitates Drill-Down Analysis

• ES can be applied to any level of the WBS, to include taskgroupings, such as the Critical Path (CP)– Requires creating PMB for the area of interest

– EV for the area of interest is used to determine its ES

• Enables comparison of forecasts, total project (TP) to CP– Desired result: forecasts are equal

– When TP forecast > CP forecast, CP has changed

– When CP > TP, possibility of future problems

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ES Bridges EVM to the Schedule

$$

Time

PV

BAC

PD

EV

ES ATAT

SV(t)

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How Can This Be Used?

• Tasks behind – possibility of impediments or constraints canbe identified

• Tasks ahead – a likelihood of future rework can be identified

• The identification is independent from schedule efficiency

• The identification can be automated

PMs can now have a schedule analysis toolconnected to the EVM Data!!

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Current Usage & Recognition

• EVM Instructors– Performance Management Associates, Management Technologies,

George Washington University, University of Florida …

• Boeing Dreamliner, Lockheed Martin, US StateDepartment, Secretary of the Air Force

• Several Countries - Australia, Belgium, United Kingdom,USA ….(Japan, Switzerland, Sweden, Spain, Brazil, India, …)

• Applications across weapons programs, construction,software development, …

• Range of project size from very small and short to extremelylarge and long duration

• Inclusion of Emerging Practice Insert into PMI - EVMPractice Standard (2004)

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Summary

• Derived from EVM data … only

• Provides time-based schedule indicators

• Indicators do not fail for late finish projects

• Application is scalable up/down, just as is EVM

• Schedule prediction is better than any other EVM methodpresently used

• Application is growing in both small and large projects

• Practice recognized as “Emerging Practice”

• Facilitates bridging EVM analysis to include the Schedule

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Thank You!

Walt Lipke

Email: [email protected]

Thank You from the MetSIG…TheInformation Highway For the Metricsof the World

earned schedule 19_earned schedule_walt lip… · • schedule variance: sv(t) = es – at •...

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