Estimate Activity

Schedule with the scope and cost is Together make the triple constraints of the project, change in one of them lead to change at least in one of the others. Therefore it's considering one of the important factors to the project success. To develop the schedule we must make accurate estimate duration for each activity but to make this we should start with resources needed for activities such as :( people, facilities, equipment, money and material)and make estimate to it .

There is different methods to estimate the duration which In my opinion all of them fall under kind of expert judgment because all the methods depend on estimate we put it therefore if want more accurate estimate must do it by the person who assigned to do the activity or expert person in the activity work one of these methods is:

1- Expert Judgment :

It is the process to gather information from outside expertise to get the necessary and appropriate evaluation of resources and time required for the implementation of the activities It is usually used when a new kind of work to the company and has no previous experience in dealing with this type of field.

2- Analogs Estimating (historical data ):

It is based on information of previous similar projects, taking account of differences and the complexity that exists between the two of them.

Where possible to use the duration and cost as well as the size and weight of the activity and the complexity of the project, from the old and used as bases for estimate similar one in the new project. Analogs are less accurate but the last one increases when the activity is similar actually real and not only apparently.

3- Parametric estimate :

It is use statistical relationship between data from previous project and other variables like labour hours per unit of work or a specific unit such as meters or number .it is more accurate and realistic Compared with analogs.

4- Delphi technique:

It is based on more than one person make a separate estimate individually. After that exchange information among them and evaluate all the estimations on the total and removed the least accurate and realistic then re-evaluate the remaining again until make the decision.

5- Three point estimate(PERT):

It is one of the most accurate and realistic estimating method and takes into consideration the risk and uncertainty factors through the adoption of three estimates:

-Optimistic (to): best -case scenario was everything goes as expected.

-Pessimistic (tP):worst-case scenario was everything goes wrong.

-Most likely (tm): realistic expectation.

And with use this