How is PERT variance calculated?

How is PERT variance calculated?

An alternative method of estimating the variance of a PERT activity time is proposed given that one of the initial estimates is the mean. The beta- distribution of the activity time is assumed to be tangential to the x-axis at each end. variance= [16 (X3-X1 ) ]2.

How do you calculate variance PERT in CPM?

CP represents activity on critical path:

1. Project duration expected E = 5 + 15 + 4 + 5 = 29 days (i.e. the total of te-s for activities on the Critical Path).
2. Variance of the Critical Path = 2.79 + 2.79 + 0.45 + 0 = 6.03.
3. Standard Deviation (SD) of project duration is √6.03 = 2.46.

What is the role of variance in PERT analysis?

The level of volatility of the time required to carry an activity from the average time is termed as variance in PERT analysis.

How do you find standard deviation from PERT?

An average expected estimate is calculated by taking a weighted average of these 3 points of estimates using below formula:E (Mean PERT Average) = (O+4ML+P)/6 (by giving more weightage to most likely estimate)Standard Deviation (SD) = (P-O)/6Actual time taken to travel will be anything within this range with the most …

How do you calculate activity variance?

PMP Formula: Variance of Activity

1. = ((P – O) ÷ 6) ^ 2.
2. = (Standard Deviation of the Activity) ^ 2.
3. O = Optimistic Estimate.
4. P = Pessimistic Estimate.

How do you calculate variance in project management?

Schedule Variance indicates how much ahead or behind schedule the project is. Schedule Variance can be calculated using the following formula: Schedule Variance (SV) = Earned Value (EV) – Planned Value (PV) Schedule Variance (SV) = BCWP – BCWS.

What is a Gert chart?

Graphical Evaluation and Review Technique, commonly known as GERT, is a network analysis technique used in project management that allows probabilistic treatment both network logic and estimation of activity duration. The technique was first described in 1966 by Dr.

How do you get the variance?

How to Calculate Variance

1. Find the mean of the data set. Add all data values and divide by the sample size n.
2. Find the squared difference from the mean for each data value. Subtract the mean from each data value and square the result.
3. Find the sum of all the squared differences.
4. Calculate the variance.

How is PERT estimate for activity duration calculated?

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.

How do you find the variance of a project?

Schedule Variance can be calculated by subtracting the Budgeted Cost of Work Scheduled (BCWS) from the Budgeted Cost of Work Performed (BCWP). BCWP measures the cost of actual work done….SV Formula

1. SV = Schedule Variance.
2. EV = Earned Value.
3. PV = Planned Value.