Activity duration estimating is the process of making a realistic quantitative assessment of the likely number of work periods that will be required to complete an activity.
The estimate is often progressively elaborated and more accurate. To ensure that the estimates at this stage are realistic, those of the project team who are more familiar with the nature of the specific activity and those who have the necessary technical knowledge or experience (by participating or managing similar activities/ projects in the past) should be consulted.
The inputs that are necessary for the activity duration estimation are:
| • | The Activity List (refer to 7.4.1.2) |
| • | Constraints and assumptions |
| • | The Resource requirements (refer to 7.4.2). The duration of most activities is influenced by the number of the resources assigned to them and by the skills and capabilities they possess. Normally, a senior consultant working full time can be expected to complete a certain activity in less time than a junior consultant, also working full time. Besides, two people from an Implementing Agency working together in a specific task are expected to complete it in half the time it takes to each of them individually. It has to be noted that although the number of the resources assigned to each task is a significant input for the activity duration estimating, there are cases in which the activity duration estimation is mainly based on historical data and experience from the implementation of previous similar projects. In these cases the activities’ duration is predetermined and the number of resources needed to carry out the activities is defined accordingly. |
| • | Historical information. This refers to data available at the project files of similar projects concerning the actual duration of their activities. It refers also to information available to databases like how long it takes concrete to cure, how long it usually takes a Ministry to respond to certain types of request, how long it takes for a law to be voted etc. |
| • | Identified risks. The project team may choose to incorporate an additional time period (usually called as reserve time) to the activity duration as recognition that one or more of the identified risks may occur. This time can be a percentage of the estimated duration or a fixed period. |
Example 7-6: Estimation of activities/ tasks duration for the Project “Improving the implementing capacity of the Cypriot Authorities”
Project: “Improving the implementing capacity of the Cypriot Authorities”. |
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Following the identification of the Project Activities (refer to 7.4.1.2), of their sequence and dependencies (refer to 7.4.1.3), the duration of the activities and tasks must be estimated. The estimation will be based on the actual duration of previous similar activities [e.g formulation of Action Plans, development of training strategy, training in legal aspects and in new processes (best practices)]. Especially for the compilation of the Best Practice Guide, the estimation of the time needed could be based on the volume of similar Guides developed by other countries or even on their experience (how long it took to them to prepare such Guides). An indicative estimation of the Activities’ duration is:
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