What are the three time estimates in PERT?

Asked By: Jannat Grotehans | Last Updated: 30th April, 2020
Category: careers vocational training
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There are three estimation times involved in PERT; Optimistic Time Estimate (TOPT), Most Likely Time Estimate (TLIKELY), and Pessimistic Time Estimate (TPESS). In PERT, these three estimate times are derived for each activity. This way, a range of time is given for each activity with the most probable value, TLIKELY.

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Likewise, people ask, what is a pert estimate?

PERT (Program Evaluation Review Technique) is an estimation technique which was first developed and applied by United States Defence establishment for their Ballistic Missile development program. Any task filled with uncertainties can have a wide range of estimate in which the task actually will get completed.

Beside above, what are the three types of estimates used in three point estimating? There are two generally accepted formulas for three point estimates: Triangular Distribution. Beta Distribution.

Triangular Distribution

  • E = estimated cost.
  • a = optimistic value.
  • m = most likely value.
  • b = pessimistic value.

Just so, how do you calculate most likely time in Pert?

Using the PERT Formula The PERT estimate (E) is based on a formula that includes your optimistic time estimate (O), your most likely time estimate (M) and your pessimistic time estimate (P). The basic equation is this: E = (O + 4M +P) / 6 .

What is PERT What is the formula you use when using PERT?

PERT calculates a weighted average as the PERT estimate by using the formula : Pert Estimate = (Optimistic + (4 X Most Likely) + Pessimistic)/6. By using the simple formula Sigma = (Pessimistic – Optimistic) / 6 we divide the graph in 6 equal blocks.

22 Related Question Answers Found

What is the formula for calculating pert?

PERT is an estimating technique that uses a weighted average of three numbers (see below) to come up with a final estimate. The resulting PERT estimate is calculated as (O + 4M + P)/6. This is called a "weighted average" since the most likely estimate is weighted four times as much as the other two values.

What is pert example?

The PERT Method – Program Evaluation and Review Technique Example & Definition. PERT Method helps to analyze the work schedule by focusing on each task and calculate the minimum time required to complete the project. In this respect, it is similar to the Critical Path Method (CPM).

What does the pert stand for?

Program Evaluation Review Technique

What does Gantt stand for?

Generalized Activity Normalization Time Table

What is the PERT method?


PERT Analysis. Program Evaluation and Review Technique (PERT) is a method used to examine the tasked that are in a schedule and determine a variation of the Critical Path Method (CPM). It analyzes the time required to complete each task and its associated dependencies to determine the minimum time to complete a project

What is the difference between CPM and PERT?

Unlike CPM, which is a method to control costs and time. While PERT is evolved as a research and development project, CPM evolved as a construction project. PERT deals with unpredictable activities, but CPM deals with predictable activities. PERT is used where the nature of the job is non-repetitive.

What is Gantt chart and PERT chart?

A PERT chart stands for “Program Evaluation and Review Technique” chart. Both of these charts are used by project managers and help in displaying the tasks which are required for project completion. The difference between them is that a Gantt chart is basically a bar chart and a PERT chart is a flow chart.

What is critical path in PERT?

The critical path method, or analysis, was developed in conjunction with PERT. Both techniques are used to manage projects within a specific timeframe. The critical path method calculates the longest path that is possible with your planned activities, then figures out the time constraints that each activity is under.

What is the formula for variance?

To calculate variance, start by calculating the mean, or average, of your sample. Then, subtract the mean from each data point, and square the differences. Next, add up all of the squared differences. Finally, divide the sum by n minus 1, where n equals the total number of data points in your sample.

What is optimistic estimate?


An optimistic estimate is what a team hopes will be the amount of time to complete their project, assuming everything goes as planned. The pessimistic estimate is the worst case scenario and is an estimate that a team would give if everything goes wrong.

What do you mean by Critical Path?

In project management, a critical path is the sequence of project network activities which add up to the longest overall duration, regardless if that longest duration has float or not. This determines the shortest time possible to complete the project.

What is 3pt analysis?

3-Points is a technique that involves people that are professional in the task we are estimating by this technique. The third estimate is the optimistic (O) estimate which is the amount of work the task might take if the positive risks they identified do occur.

What is the purpose of schedule contingency reserve?

The contingency reserve is used to manage identified risks, while the management reserve is used for unidentified risks. The contingency reserve is an estimated figure, while the management reserve is a percentage of the cost or duration of the project.

What does triple constraint mean?

The triple constraint is the combination of the three most significant restrictions on any project: scope, schedule and cost. The triple constraint is sometimes referred to as the project management triangle or the iron triangle.

What formula can a project manager use to estimate task duration provide an example?


A project manager use a weighted formula to estimate task duration (B+4P+W) /6 Example: A project manager makes an estimate that a file-conversion task could be completed in as few as 20 days or could take as many as 34 days, but most likely will require 24 days. (20+ (4*24) +34)/6=25 7.

Is a project charter a contract?

A Project charter recognizes & authorizes the project within an organization and authorizes the start of the project whereas a Contract is a legally binding agreement between two different organizations (the Buyer and the Seller).

How do you estimate a project timeline?

3 General Rules for Better Estimating
  1. Write stuff down. Writing forces you to expose all the hidden assumptions you're making when you're thinking through things.
  2. It's ok to be uncertain.
  3. Ask your peers.
  4. Break the Project into Tasks.
  5. Determine the Overall Objective.
  6. Identify Outlying Factors Needed for Success.