BSBPMG503A Manage Project Time

6.4 Estimate Activity Duration

• The process of approximating the number of work periods needed to complete individual activities with the assigned or estimated resources

• Previous experience in the type of project and activities being estimated greatly helps with the accuracy of duration estimates

• Duration is a function of work effort and resources

• Most project management software can perform this function

• Occurs during the Planning Phase

Adapted from PMBOK 4th Edition

Initiation Planning Execution Close

Monitor

Control

BSBPMG503A Manage Project Time

6.4 Estimate Activity Duration

• Inputs to Estimate Activity Duration

Activity list and attributes

Activity Resource requirements and estimates

Resource Calendars

Project Scope Statement

Productivity metrics and estimating data

• Tools and techniques to Estimate Activity Duration

Adapted from PMBOK 4th Edition

Three-PointEstimating

ExpertJudgement

AnalogousEstimating Parametric

Estimating

ReserveAnalysis

BSBPMG503A Manage Project Time

6.4 Estimate Activity Duration

• Analogous EstimatingDevelops duration estimates based on previous projects with

similar size, risk and complexity

Relies heavily of expert judgement and previous experience

Less costly and less time consuming than other methods

Least accurate

Most common form of duration estimating

• Parametric EstimatingDuration is quantified by multiplying the quantity of work by

the labour hours required

Relies on published estimating data

Common in Construction

Initiation Planning Execution Close

Monitor

Control

Adapted from PMBOK 4th Edition

BSBPMG503A Manage Project Time

6.4 Estimate Activity Duration

• Three-Point Estimates - PERT

Calculates the Expected activity duration based on the weighted average of the Most Likely, Optimistic and Pessimistic estimates

Often more accurate than other methods and quantified range of uncertainty

• Reserve Analysis

Inclusion of contingency

Can be calculated for each activity

Can be calculated for entire project

Often a percentage based on risk or complexity

Initiation Planning Execution Close

Monitor

Control

Adapted from PMBOK 4th Edition

BSBPMG503A Manage Project Time

6.4 Estimate Activity Duration

• The major output of this process

Activity Duration Estimates

Draft or High Level Project Duration Estimate

• Often include some form of range of possible results

• Most common form of range is plus or minus - eg

2 weeks +/- 2 days – the activity could take between 8 and 12 days

3 weeks +/- 30% - the activity could take between 2 weeks and 4 weeks

Adapted from PMBOK 4th Edition

Initiation Planning Execution Close

Monitor

Control