## How To Get Statistics Question Right On The PMP Exam

This page is currently under development, we have plans to expand through these next couple weeks.

This first section focuses on dealing with Network Diagrams. If you need help with Network Diagrams please take a look at my Network Diagrams Study Guide.

In the future, we plan to add sample questions more specific to what you will find on the test that will help you master all of these topics.

## Statistical Ideas Related to Network Diagrams

When dealing with Network Diagram questions on the PMP exam you may be asked to perform some statistical analysis on the data that you either find or is provided to you. This section focuses on giving you all the information you need to answer these types of questions.

## Three Point Estimating

When estimating activity durations or costs the accuracy of a single estimate may not be good enough. At that point we may go to a three point estimate. The three point estimate looks at the:

- Most likely Estimate (ML)
- Pessimistic Estimate (P)- sometimes called worst case
- Optimistic Estimate (O)-sometimes call best case

To calculate duration (or cost) estimates with three points we may use:

#### Simple Average Estimate (Triangle Distribution)

Simple Average Estimate = (P + ML + O) ÷ 3

#### PERT (Beta Distribution)

PERT estimate = (P + 4ML + O) ÷ 6

## Standard Deviation and Variance for an Activity

Standard Deviation is a measure of the amount of variation we have in a set of data. The larger the standard deviation the larger the variation. The smaller the standard deviation the small the variation.

To calculate Standard Deviation or Variance given Most Likely, Pessimistic, and Optimistic Estimates for the duration of the activity:

#### Standard Deviation for an Activity

Standard Deviation = | (pessimistic - optimistic) ÷ 6|

SD = | (P - O) ÷ 6|

#### Variance for an Activity

Variance = (SD)^{ 2}

## Standard Deviation for an Activity

This quiz only pertains to the formula for Standard Deviation for an Activity! Goodluck!

Click the button below to start.

## Variance for an Activity

This quiz only pertains to the formula for Variance for an Activity! Goodluck!

Click the button below to start.

## Standard Deviation and Variance for a Path

These ideas when applied to a path are very difficult and don’t represent the difficulty of the PMP exam. That said, they could be tested so I have included them here. Use these as practice for mastering your calculations when dealing with an Activity.

There are six possible steps when dealing with Standard Deviation for a path:

- Determine the Duration Uncertainty for each activity
- Determine the Standard Deviation for each activity
- Determine the Variance of each activity
- Determine the Project Variance for the remaining path
- Determine the Standard Deviation for the remaining path
- Determine duration uncertainty for the remaining path

#### Duration Uncertainty for an Activity

Duration Uncertainty = P - O

#### Variance for a Path

Variance for a Path = Σ Variance for each Activity

Variance for a Path = Variance for Activity A + Variance for Activity B + ...

#### Standard Deviation for a Path

Standard Deviation for a Path = Square root of Path Variance

Standard Deviation for a Path = √(Path Variance)

#### Duration Uncertainty for a Path

Duration Uncertainty for a Path is the same as ± 3 Standard Deviation. Therefore multiply one standard deviation by 6

Duration Uncertainty for a Path = SD * 6

## Standard Deviation and Variance for a Path

This test is much more challenging than what you will (most likely) find on the PMP Exam and your time is better spent studying other tasks.

However, if you are up to the challenge these questions are based on the equations above.

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