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MS Project SPI Calculations confusion

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Melissa Hellas Tsalicoglou Abu Dhabi, Khalifa City A, United Arab Emirates
Struggling to understand the SPI calculation in my schedule, hoping someone can shed some much needed light on the matter:

I have the following data:

I cant figure out why if the baseline finish is 17 October and the actual finish of the task is 6th November it shows an SPI of 1?


Baseline start Oct 20 '19 Baseline Finish Oct 30 '19
Actual start Oct 20 '19 Actual Finish Nov 6 '19
CPI is 0.56 (meaning we spent more money than we planned by 44%)

Using MS project Online Desktop client
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Melissa Hellas Tsalicoglou Abu Dhabi, Khalifa City A, United Arab Emirates
Nov 06, 2019 9:28 AM
Replying to Julie Ann Jones
...
Hi Melissa, Kamwa is correct
I hope this example will assist…. SPI = EV/PV.
SPI measures the efficiency of the schedule
EV earned value – (work performed - how much did I get done, budget cost)
PV planned value - (the ‘promise’ – how much will it cost, the budget of all work planned)
AC actual cost – (how much it actually cost in reality)

PV – the ‘promise’ was start Oct 20 and finish Oct 30 (10 days) you need the monetary value for each day, for example $100 per day = 10 days @ $100/day, therefore PV ‘promise’ is $1,000
EV – how much work did you get done by Oct 30, example 80% of $1,000 = $800

SPI = EV/PV $800/$1000 = 0.8, therefore behind schedule.

Based on the example value figures your AC would be
AC Actual Cost – how much it actually cost, Oct 20 to Nov 6 (17 days), 17 x $100 = $1,700
@Julie one more situation which shows SPI of 1.14 at 100% completion. I was understanding the when a task is 100% the SPI goes to 1 regardless if its past the baseline finish date
There must be something I am missing the understanding this SPI
Baseline start date 4 Nov and baseline Finish date 10 Nov ( 4 days) The work started on the 5 Nov and ended on 5 Nov SPI is 1.14 at 100% completion
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Asif Gul Consultant Project Manager| Energoprojekt Entel Muscat, Oman
I also have same confusion hence i don't use EVM as it does not take into consideration the time factor separately, but it relate project time with its cost value.. In my understanding, in the Earned Value System all the values .i.e. EV, PV & AC are represented in terms of cost, like EV= is cost value of work done , PV= Cost value of work planned and AC= Actual cost.
You are getting result 1 for SPI at the end of project( SPI= EV/PV ) because when you are calculating both value of work done (EV) and value of work planed became equal. For CPI since you are putting actual cost which is more than planned/earned value hence CPI is giving accurate result. Hence you are right in the end schedule performance Index does not matter or you have to replace the PV with actual cost.
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Julie Ann Jones Lincs, Lincolnshire, United Kingdom
Hi Melissa

SPI is used for tracking the progress of your on-going project and provides that early warning signal, are you ahead or behind schedule, it is the ratio of work actually completed to planned but measured in $ rather than time, which may be confusing to anyone new to EVM.

SPI following project completion, late or otherwise will always be 1 as this represents unity and is therefore a great asset as that early warning signal throughout the project to detect problems or opportunities, are you on track, what do you need to do if not, used in conjunction with CPI, further EVM formulas may then be of assistance.

There is an extension to the theory and practice of EVM, namely ES Earned Schedule, ES and AT (Actual Time), which is mentioned within the current BMBOK (p.233), sub heading ‘Trends and Emerging Practices in Project Cost Practices’. The SPI using ES metrics is ES/AT.
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Eduard Hernandez
Community Champion
Product Operations Program Manager Barcelona, Cataluña, Spain
SPI is not such a useful indicator in projects that are about 2/3 or more completed (in terms of earned value) given that it tends towards one, even if project is very delayed (at the end of the project all value has been earned, even if it has earned with one year delay, thus SPI will equal 1, and close to one in the months before that). Check out earned schedule management to learn more about this.

I am aware that this doesn't answer your question, but hope that it gives some alternative insight.
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