Project Estimation

Most difficult activity in project management is estimate the time. There are mainly five methods to estimate the time.

1. Gusstimating


2. Delphi Technique


3. Time Boxing


4. Top-Down Estimating


5. Bottom-Up Estimating

Gusstimating

This is not a best way to do the estimating. Just picking numbers out of the air. Many inexperience project managers use this, because this is quick and easy. There is no logical reasons to explain the estimate values.

Delphi Technique

In this technique number of experts are used to estimate the values for the same activity. After that these estimated values are compared. If values are reasonable close, then take the average value as an estimated value. If values are not closer, estimated values are distributed again among experts and discuss about the difference and do the estimation again.
This is the most expensive and time consuming estimation technique. However error is very low in this and also highly effective.

Time Boxing

Box of time is allocated for a specific activity. This is based on the requirements. After end of the allocated time period work is stopped whether it is finished or not.

Top-Down Estimating

This estimation starts after schedule is identified. Project manager can allocate percentage of time for each activity. Data from the previous projects are very useful for this.

Bottom-Up Estimating

This is the most common estimation technique. Project is divided into small units and time is allocated for each model. WBS is the basis for the Bottom up estimation.