This Guest case study was submitted for publication 8/15/13. It is copyright to Young Min Park, PMP MSPM, 2013. Published here March 2014

## Estimating Activity Durations and Project Duration

### Activity duration estimating

There are number of techniques for determining durations and one is "Parametric Estimating". In this technique, "Estimating the basis for activity duration can be quantitatively determined by dividing the quantity of work to be performed by the productivity rate. Below is a specific example of "parametric estimating" that is found in Eojeseonghwajuryak.

##### Figure 26: Eojeseonghwajuryak

Translation of extract shown in yellow:

"It is estimated that one carriage need two heads of cattle. There are 3,600 carriage stones required for one layer of the wall, and it would be 32,400 carriage stones would be consumed for 9 layers of the wall. Therefore, it would take 154 days with 70 cattle carriages, if one cattle carriage transports stones 3 time per day."

### Project duration estimate

In many cases, when the initial project duration is being estimated, "expert judgment" and/or "historical information" would be a valuable reference tool. Project Manager Cho Simtae seemed to use this technique. So when 10 months before the project, the King asked Cho Simtae about the estimated duration, Cho Simtae said it would be 10 years depending on the money and resources available, see Figure 27.

##### Figure 27: Yeonsul, December 6, 1793

Translation of extract shown in yellow:

"The King asked 'How long do you estimate the duration of the fortress project?' Yeoyoungdaejang Cho Simtae answered 'Though it is estimated 10 years, it would be difficult to make it earlier as we need to prepare enough money, materials, and skilled people and it might otherwise cause the delay of the project'"