(1) Explain your problem, don't simply post "This isn't working". What were you doing when you faced the problem? What have you tried to resolve - did you look for a solution using "Search" ? Has it happened just once or several times?
(2) It's also good to get feedback when a solution is found, return to the original post to explain how it was resolved so that more people can also use the results.
For all planners are keep asking about S-Curve
the Artical has been written By: David Garland
Introduction
The first time most project managers become aware of the existence of S-curves is when they are requested by the client or senior management to include one in their next progress report. The following explains what the mysterious S-curve is, why it is an important project management tool, and how to generate one.
Editor's Note:
The S-curve is a powerful project management control tool. Why it is the shape it is, how to use it and "Max's Rule of Thumb" for drawing it as a part of the project planning activity are all described in Chapter 10 of A Management Framework for Project, Program and Portfolio Integration. You can also find more information on this web site by entering "S-curve" or "Resource loading" into the site search engine field.
An S-curve is defined as:
"A display of cumulative costs, labor hours or other quantities plotted against time. The name derives from the S-like shape of the curve, flatter at the beginning and end and steeper in the middle, which is typical of most projects. The beginning represents a slow, deliberate but accelerating start, while the end represents a deceleration as the work runs out."[1]
There are a variety of S-curves that are applicable to project management applications, including:
Each of these is described in the following pages.
The Man Hours versus Time S-curve is appropriate for projects that are labor intensive. It shows cumulative man hours expended over time for the duration of the project. As man-hours are a product of manpower and working hours, these may be adjusted together or individually in an attempt to keep the project on schedule. Projects may require additional man-hours to finish on time due to low productivity, delays and disruptions, rework, variations, etc.
By: David Garland
What is the S-Curve, and how do calculate the work progress..
Introduction
The first time most project managers become aware of the existence of S-curves is when they are requested by the client or senior management to include one in their next progress report. The following explains what the mysterious S-curve is, why it is an important project management tool, and how to generate one.
Editor's Note:
The S-curve is a powerful project management control tool. Why it is the shape it is, how to use it and "Max's Rule of Thumb" for drawing it as a part of the project planning activity are all described in Chapter 10 of A Management Framework for Project, Program and Portfolio Integration. You can also find more information on this web site by entering "S-curve" or "Resource loading" into the site search engine field.
An S-curve is defined as:
"A display of cumulative costs, labor hours or other quantities plotted against time. The name derives from the S-like shape of the curve, flatter at the beginning and end and steeper in the middle, which is typical of most projects. The beginning represents a slow, deliberate but accelerating start, while the end represents a deceleration as the work runs out."[1]
There are a variety of S-curves that are applicable to project management applications, including:
Each of these is described in the following pages.
The Man Hours versus Time S-curve is appropriate for projects that are labor intensive. It shows cumulative man hours expended over time for the duration of the project. As man-hours are a product of manpower and working hours, these may be adjusted together or individually in an attempt to keep the project on schedule. Projects may require additional man-hours to finish on time due to low productivity, delays and disruptions, rework, variations, etc.
The Costs versus Time S-curve is appropriate for projects that contain labor and non-labor (e.g. material supply / hire / subcontract) tasks. It shows cumulative costs expended over time for the duration of the project, and may be used to assist in the calculation of the project's cash flow, and cost to complete.
Prior to project commencement, a schedule is prepared outlining the proposed allocation of resources and the timing of tasks necessary to complete the project within a set time frame and budget. This schedule is referred to as the Baseline Schedule. From this schedule, a Baseline S-curve is generated. This S-curve reflects the planned progress of the project. If the project requirements change prior to commencement (e.g. change of scope, delayed start), the Baseline Schedule may require revision to reflect the changed requirements.
Following project commencement, modification of the Baseline Schedule is usually required. Changes are continually made to the Production Schedule (which is originally the same as the Baseline Schedule). The production schedule reflects the actual progress of the project to date, and any revisions made to tasks yet to commence or not yet completed. From this schedule, a Target S-curve may be generated. This S-curve reflects the ideal progress of the project if all tasks are completed as currently scheduled. In an ideal world, the Target S-curve will meet the Baseline S-curve at the end of the project (On Time, On Budget) or finish below and to the left of the Baseline S-curve (Early, Under Budget). In reality, it is not uncommon for the Target S-curve to finish above and to the right of the Baseline S-curve (Late, Over Budget).
The production schedule is updated on a regular basis throughout the duration of the project. These updates include the revision of percentage complete for each task to date. Using this information, an Actual S-curve may be generated. This S-curve reflects the actual progress of the project to date, and may be compared with the Baseline and Target S-curves to determine how the project is progressing. During the project, the Actual S-curve will terminate at the Cut Off Date. This is the date the Production Schedule was last updated. At the completion of the project, the Actual S-curve will meet the Target S-curve.
S-curves may be graphed as absolute values (i.e. Man Hours or Costs) versus Time, or as percentage values versus Time. Value S-curves are useful for determining Man Hours or Costs expended to date, and Man Hours or Costs to complete. Percentage S-curves are useful for calculating the project's actual percentage complete against target and baseline percentage complete, and for calculating the project's percentage growth (or contraction).
S-curves are an important project management tool. They allow the progress of a project to be tracked visually over time, and form a historical record of what has happened to date. Analyses of S-curves allow project managers to quickly identify project growth, slippage, and potential problems that could adversely impact the project if no remedial action is taken.
Comparison of the Baseline and Target S-curves quickly reveals if the project has grown (Target S-curve finishes above Baseline S-curve) or contracted (Target S-curve finishes below Baseline S-curve) in scope. A change in the project's scopes implies a re-allocation of resources (increase or decrease), and the very possible requirement to raise contract variations. If the resources are fixed, then the duration of the project will increase (finish later) or decrease (finish earlier), possibly leading to the need to submit an extension of time claim.
Slippage is defined as:
"The amount of time a task has been delayed from its original baseline schedule. The slippage is the difference between the scheduled start or finish date for a task and the baseline start or finish date. Slippage can occur when a baseline plan is set and the actual dates subsequently entered for tasks are later than the baseline dates or the actual durations are longer than the baseline schedule durations".[2]
Comparison of the Baseline S-curve and Target S-curve quickly reveals any project slippage (i.e. the Target S-curve finishes to the right of the Baseline S-curve). Additional resources will need to be allocated or additional hours worked in order to eliminate (or at least reduce) the slippage. An extension of time claim may need to be submitted if the slippage cannot be eliminated or reduced to an acceptable level.
Comparison of the Target S-curve and Actual S-curve reveals the progress of the project over time. In most cases, the Actual S-curve will sit below the Target S-curve for the majority of the project (due to many factors, including delays in updating the production schedule). Only towards the end of the project will the curves converge and finally meet. The Actual S-curve can never finish above the Target S-curve. If the Actual S-curve sits above the Target S-curve at the Cut Off Date, the Production Schedule should be examined to determine if the project is truly ahead of schedule, or if the Production Schedule contains unrealistic percentage complete values for ongoing tasks.
Percentage S-curves may be used to calculate important project benchmarks on an ongoing basis, including:
To generate a Baseline S-curve, a Baseline Schedule is required.
The Baseline Schedules should contain the following information for each task:
To generate Actual and Target S-curves, a Production Schedule is required.
The Production Schedules should contain the following information for each task:
To better understand how S-curves are generated, consider a simple project comprising three tasks.
A Baseline Schedule prepared using MS Project for this project is shown below.
To generate a Baseline Man Hours versus Time S-curve, two sets of calculations are performed.
The first set of calculations is performed for each task in the Baseline Schedule.
These calculations are shown in the following table.
The second set of calculations is performed for each day in the Baseline Schedule.
These calculations are shown in the following table.
The S-curve is constructed by assigning the Dates to the X Axis, and the YTD values to the Y Axis.
The resulting Baseline Man Hours versus Time S-curve is shown below.
To generate the Actual and Target S-curves, a Production Schedule is required. A Production Schedule for this project is shown below.
To generate a Target Man Hours versus Time S-curve, two sets of calculations are necessary. The first set of calculations is performed for each task in the Production Schedule.
These calculations are shown in the following table.
The second set of calculations is performed for each day in the Production Schedule.
These calculations are shown in the following table:
The resulting Target Man Hours versus Time S-curve is shown below.
To generate an Actual Man Hours versus Time S-curve, two sets of calculations are performed, but before these calculations may be performed, the Cut Off Date needs to be defined. This is the date the Production Schedule was last updated. For this example a Cut Off Date of 3rd November 2008 will be used.
The first set of calculations is performed for each task in the Production Schedule.
These calculations are shown in the following table.
The second set of calculations is performed for each day in the Production Schedule up to the Cut Off Date.
These calculations are shown in the following table.
The resulting Actual Man Hours versus Time S-curve is shown below.
The Baseline, Actual, and Target S-curves are usually combined, as shown below.
Analysis
S-curve Analysis
Initial examination of the S-curves generated above reveal the following about the status of the project.
Project Growth
Analysis of the Baseline and Target S-curve data reveals the project has grown in scope by 12 man-hours, or 14.29%.
Project Slippage
Analysis of the Baseline and Target S-curve data reveals the project has slipped by 1 day, or 20.00%.
Project Progress
According to MS Project, based on the Production Schedule the project is 50% complete. MS Project calculates percentage complete based on durations, and does not take into account man-hours assigned to each task. Analysis of the Actual and Target S-curve data reveals the project is 53.13% complete as of the Cut Off Date, while the project should be 59.38% complete.
The project will finish late and over budget compared to the Baseline Schedule. Progress to date (i.e. the Cut Off Date) is behind schedule compared to the Production Schedule. Detailed analysis of the project is required to determine why the project will be completed late and over budget. Project growth and/or slippage may be due to a number of factors, including underestimation of effort in the Baseline Schedule, low productivity, rework, variations (approved or not), etc.
In this example, variations may need to be raised to account for the extra man hours expended, and an extension of time claim raised for the later than planned completion. The Production Schedule may need review to ensure tasks have been updated accurately (especially with respect to true percentage complete values), and ongoing and future tasks may require revising.
Some software scheduling packages automatically generate S-curves. On the other hand, some (including MS Project) do not. In this case, a third party software application is required to process the Baseline and Production Schedule data to generate the required S-curves.
Midori Media's myPM SCG S-curve Generator is an MS Windows application that integrates with MS Excel to generate the various types of S-curves discussed above. MS Project users will need to export their schedule data to an MS Excel file (easily accomplished using MS Project's File Save As option). myPM SCG processes the resulting export file, and creates an MS Excel Output file containing the required S-curves. These may be copy-pasted to MS Word for inclusion in Project Progress Reports.
The S-curve is an important but often overlooked and misunderstood project management tool. A variety of S-curves exist, the most common being Man Hours versus Time, and Costs versus Time. By creating a Baseline Schedule, a Baseline S-curve can be generated. Baseline S-curves provide a basis on which to compare a project's actual status to its planned status. They may also assist in the planning of manpower and financial resources required to complete the project.
A Production Schedule allows Actual and Target S-curves to be generated. These allow the progress of a project to be monitored, and quickly reveal any divergence from the Baseline Schedule. S-curves may also be used to determine project growth, slippage, and progress to date.
The Costs versus Time S-curve is appropriate for projects that contain labor and non-labor (e.g. material supply / hire / subcontract) tasks. It shows cumulative costs expended over time for the duration of the project, and may be used to assist in the calculation of the project's cash flow, and cost to complete.
Prior to project commencement, a schedule is prepared outlining the proposed allocation of resources and the timing of tasks necessary to complete the project within a set time frame and budget. This schedule is referred to as the Baseline Schedule. From this schedule, a Baseline S-curve is generated. This S-curve reflects the planned progress of the project. If the project requirements change prior to commencement (e.g. change of scope, delayed start), the Baseline Schedule may require revision to reflect the changed requirements.
Following project commencement, modification of the Baseline Schedule is usually required. Changes are continually made to the Production Schedule (which is originally the same as the Baseline Schedule). The production schedule reflects the actual progress of the project to date, and any revisions made to tasks yet to commence or not yet completed. From this schedule, a Target S-curve may be generated. This S-curve reflects the ideal progress of the project if all tasks are completed as currently scheduled. In an ideal world, the Target S-curve will meet the Baseline S-curve at the end of the project (On Time, On Budget) or finish below and to the left of the Baseline S-curve (Early, Under Budget). In reality, it is not uncommon for the Target S-curve to finish above and to the right of the Baseline S-curve (Late, Over Budget).
The production schedule is updated on a regular basis throughout the duration of the project. These updates include the revision of percentage complete for each task to date. Using this information, an Actual S-curve may be generated. This S-curve reflects the actual progress of the project to date, and may be compared with the Baseline and Target S-curves to determine how the project is progressing. During the project, the Actual S-curve will terminate at the Cut Off Date. This is the date the Production Schedule was last updated. At the completion of the project, the Actual S-curve will meet the Target S-curve.
S-curves may be graphed as absolute values (i.e. Man Hours or Costs) versus Time, or as percentage values versus Time. Value S-curves are useful for determining Man Hours or Costs expended to date, and Man Hours or Costs to complete. Percentage S-curves are useful for calculating the project's actual percentage complete against target and baseline percentage complete, and for calculating the project's percentage growth (or contraction).
S-curves are an important project management tool. They allow the progress of a project to be tracked visually over time, and form a historical record of what has happened to date. Analyses of S-curves allow project managers to quickly identify project growth, slippage, and potential problems that could adversely impact the project if no remedial action is taken.
Comparison of the Baseline and Target S-curves quickly reveals if the project has grown (Target S-curve finishes above Baseline S-curve) or contracted (Target S-curve finishes below Baseline S-curve) in scope. A change in the project's scopes implies a re-allocation of resources (increase or decrease), and the very possible requirement to raise contract variations. If the resources are fixed, then the duration of the project will increase (finish later) or decrease (finish earlier), possibly leading to the need to submit an extension of time claim.
Slippage is defined as:
"The amount of time a task has been delayed from its original baseline schedule. The slippage is the difference between the scheduled start or finish date for a task and the baseline start or finish date. Slippage can occur when a baseline plan is set and the actual dates subsequently entered for tasks are later than the baseline dates or the actual durations are longer than the baseline schedule durations".[2]
Comparison of the Baseline S-curve and Target S-curve quickly reveals any project slippage (i.e. the Target S-curve finishes to the right of the Baseline S-curve). Additional resources will need to be allocated or additional hours worked in order to eliminate (or at least reduce) the slippage. An extension of time claim may need to be submitted if the slippage cannot be eliminated or reduced to an acceptable level.
Comparison of the Target S-curve and Actual S-curve reveals the progress of the project over time. In most cases, the Actual S-curve will sit below the Target S-curve for the majority of the project (due to many factors, including delays in updating the production schedule). Only towards the end of the project will the curves converge and finally meet. The Actual S-curve can never finish above the Target S-curve. If the Actual S-curve sits above the Target S-curve at the Cut Off Date, the Production Schedule should be examined to determine if the project is truly ahead of schedule, or if the Production Schedule contains unrealistic percentage complete values for ongoing tasks.
Percentage S-curves may be used to calculate important project benchmarks on an ongoing basis, including:
To generate a Baseline S-curve, a Baseline Schedule is required.
The Baseline Schedules should contain the following information for each task:
To generate Actual and Target S-curves, a Production Schedule is required.
The Production Schedules should contain the following information for each task:
To better understand how S-curves are generated, consider a simple project comprising three tasks.
A Baseline Schedule prepared using MS Project for this project is shown below.
To generate a Baseline Man Hours versus Time S-curve, two sets of calculations are performed.
The first set of calculations is performed for each task in the Baseline Schedule.
These calculations are shown in the following table.
The second set of calculations is performed for each day in the Baseline Schedule.
These calculations are shown in the following table.
The S-curve is constructed by assigning the Dates to the X Axis, and the YTD values to the Y Axis.
The resulting Baseline Man Hours versus Time S-curve is shown below.
To generate the Actual and Target S-curves, a Production Schedule is required. A Production Schedule for this project is shown below.
To generate a Target Man Hours versus Time S-curve, two sets of calculations are necessary. The first set of calculations is performed for each task in the Production Schedule.
These calculations are shown in the following table.
The second set of calculations is performed for each day in the Production Schedule.
These calculations are shown in the following table:
The resulting Target Man Hours versus Time S-curve is shown below.
To generate an Actual Man Hours versus Time S-curve, two sets of calculations are performed, but before these calculations may be performed, the Cut Off Date needs to be defined. This is the date the Production Schedule was last updated. For this example a Cut Off Date of 3rd November 2008 will be used.
The first set of calculations is performed for each task in the Production Schedule.
These calculations are shown in the following table.
The second set of calculations is performed for each day in the Production Schedule up to the Cut Off Date.
These calculations are shown in the following table.
The resulting Actual Man Hours versus Time S-curve is shown below.
The Baseline, Actual, and Target S-curves are usually combined, as shown below.
Analysis
S-curve Analysis
Initial examination of the S-curves generated above reveal the following about the status of the project.
Project Growth
Analysis of the Baseline and Target S-curve data reveals the project has grown in scope by 12 man-hours, or 14.29%.
Project Slippage
Analysis of the Baseline and Target S-curve data reveals the project has slipped by 1 day, or 20.00%.
Project Progress
According to MS Project, based on the Production Schedule the project is 50% complete. MS Project calculates percentage complete based on durations, and does not take into account man-hours assigned to each task. Analysis of the Actual and Target S-curve data reveals the project is 53.13% complete as of the Cut Off Date, while the project should be 59.38% complete.
The project will finish late and over budget compared to the Baseline Schedule. Progress to date (i.e. the Cut Off Date) is behind schedule compared to the Production Schedule. Detailed analysis of the project is required to determine why the project will be completed late and over budget. Project growth and/or slippage may be due to a number of factors, including underestimation of effort in the Baseline Schedule, low productivity, rework, variations (approved or not), etc.
In this example, variations may need to be raised to account for the extra man hours expended, and an extension of time claim raised for the later than planned completion. The Production Schedule may need review to ensure tasks have been updated accurately (especially with respect to true percentage complete values), and ongoing and future tasks may require revising.
Some software scheduling packages automatically generate S-curves. On the other hand, some (including MS Project) do not. In this case, a third party software application is required to process the Baseline and Production Schedule data to generate the required S-curves.
Midori Media's myPM SCG S-curve Generator is an MS Windows application that integrates with MS Excel to generate the various types of S-curves discussed above. MS Project users will need to export their schedule data to an MS Excel file (easily accomplished using MS Project's File Save As option). myPM SCG processes the resulting export file, and creates an MS Excel Output file containing the required S-curves. These may be copy-pasted to MS Word for inclusion in Project Progress Reports.
The S-curve is an important but often overlooked and misunderstood project management tool. A variety of S-curves exist, the most common being Man Hours versus Time, and Costs versus Time. By creating a Baseline Schedule, a Baseline S-curve can be generated. Baseline S-curves provide a basis on which to compare a project's actual status to its planned status. They may also assist in the planning of manpower and financial resources required to complete the project.
A Production Schedule allows Actual and Target S-curves to be generated. These allow the progress of a project to be monitored, and quickly reveal any divergence from the Baseline Schedule. S-curves may also be used to determine project growth, slippage, and progress to date.
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Expert Project Management - The Mysterious S-curve
OOPS - Seems like the author forgot about early and late S-curves, it is an abysmal omission!
On the other hand the following author did not forgot late curves for Current Schedule while for Baseline he forgot also Baselines have late S curves.
Understanding-Project-S-Curves.pdf
Hi all,
I'w working on a shutdown schedule and want to generate S curve by WBS level. I created a layout for each WBS level and generate my curve. But the problem here is : I have 16 WBS levels and it will cost me a lot of time to print one by one.
Is there a solution to print all the curves in one shot ? one file ?
Thanks for your feedback.
Morne Beeslaar warning on productivity rates being at best a guess cannot be overlooked. No way can you overlook the reliability of the source data you uses when creating the S-curves.
· You need to track production rates.
· Easier to track if using Unit Costing capable financial/accounting software. The mere tracking of budgeted amounts is not good enough.
· https://www.foundationsoft.com/unit-cost-production-reporting/
· Easier to model if using scheduling software that correctly model production rates in easy to understand implementation instead of missing this important value .
· https://www.slideshare.net/davilara11/enhanced-resource-planning
There are a variety of S-curves that are applicable to project management applications, including: Man Hours versus Time S-curve, Costs versus Time S-curve, Baseline S-curve, Actual S-curve, Target S-curve, Value and Percentage S-curves.
· Some important S-curves any scheduler shall understand are missing:
· The Probabilities of Success curve.
· http://www.goodplan.ca/2011/02/s-curve-of-success.html
· EVM S-curves.
· https://josephzaarour.wordpress.com/tag/earned-value/
Also is missing the misconceptions and pitfalls of some S-curves that shall be included in any reference to S-curves for it to be complete.
Good information and theoretically sound.
Problem in South Africa is that contractors are notoriously poor at just producing a level 3 schedule never mind getting cost or resource loading done to produce manhour schedules. Productivity rates are at best a guess.
Thanks for a great article though.
Dear, this article is originally available at http://www.maxwideman.com/guests/s-curve/intro.htm
hi
we can not display the pictures
hi
I tried this link: http://www.projectmagazine.com/monitoring-and-controlling/62-communication/404-the-mysterious-s-curve
but I get "server not found" error.
Hi, It is a good article but I can not see the pictures,
how can i disply them?
tnx.
good article but pictures are not displaying.
Hi,
where I can get pictures , that would be easier to understand
It is a good article, but unfortunately, the picture in it can not display normally.
Email: PPadmin@planningplanet.com
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