The original version of this paper was published here in May 2009: See S-curve/intro.htm This 4th Edition was submitted for publication in January 2019. It is copyright © Midori Media. Published here September 2019.

## Using Task Duration as a Quantity

Extreme caution should be exercised when using Task Duration as a quantity to generate S‑curves.

Consider the following Production Schedule.

 Task Name Start Finish Man Hours % Complete Duration MH per Day Task No. 1 01‑Feb‑2016 05‑Feb‑2016 10.0 40% 5 2.0 Task No. 2 02‑Feb‑2016 05‑Feb‑2016 20.0 30% 4 5.0 Task No. 3 03‑Feb‑2016 05‑Feb‑2016 30.0 20% 3 10.0 Task No. 4 04‑Feb‑2016 05‑Feb‑2016 140.0 0% 2 70.0 Totals 200.0 14
##### Table 12: Production Schedule

The % Complete values represent the Task's physical percentage completion, as inspected on 4th February 2016 (The Cut Off Date).

The S-curves generated using Task Duration as the Quantity are shown in Figure 20.

##### Figure 20: Percentage Task Duration S-curves (Target = 100%)

Analysis of the above S-curves reveals the Project as of the 4th of February 2016:

• Is 27.86% Complete (Actual)
• Should be 42.86% Complete (Target)
• Is 15.00% behind target (42.86 - 27.86)

The S-curves generated using Task Man Hours as the Quantity are shown in Figure 21.

##### Figure 21: Percentage Task Man Hours S-curves (Target = 100%)

Analysis of the above S-curves reveals the Project as of the 4th of February 2016 is:

• 7.95% Complete (Actual)
• Should be 13.00% Complete (Target)
• 5.05% behind target (13.00 - 7.95)

A comparison of the above figures reveal using Task Duration as a quantity paints a very different picture of the Project's progress as compared to using Task Man Hours as a quantity.

The reason for the variance in the Project's progress is that by using Task Duration as a quantity, the assumption is all Tasks require exactly the same amount of Man Hours per Day. This is often not the case in real life.

In Part 4 I will justify why S-curves are so important as a reporting tool

 Generating Percentage S‑curves PART 4