Estimating Task Durations

Methodologies and Psychologyof Estimating

Project Schedules and Estimates

Accuracy at the task level translates up to the accuracy at the project level

Consistency is key

Estimating the unknownHow long does it take to catch a fish?

Might be right away

Might be never

Might be anything in between

Estimating the unknownApply metrics to the madness

What is ‘most likely’ to happen?

Estimating the unknownWhat are the required ‘tools’ to complete the task?

Do we need to acquire the tools before attempting the task?

Estimating the unknownMultiple tasks create an accumulation of guesses

‘Buffers’ 5+5=13

So what do we do? Buffers are not secrets

Everyone knows durations are buffered

What Does the Task Duration Really

Represent?Discussion

Here are several approaches to estimating

task durations: Elapsed Time vs. Working Time

Task Time vs. Resource Time

Interface Losses & Delays

Theoretical Duration vs. Experience

Elapsed Time vs. Working Time

We don’t work ALL the time

Task Time vs. Resource Time

The number of people involved affects the elapsed time

Interface Losses & Delays

How do we represent these spans of time to accommodate ‘buffers’ / ‘losses’?

Theoretical Duration vs. Experience

What I know SHOULD happenvs.What I know Will happen

Here are a few traps to note:

Traps: MathImproper use of averaging

Trap: Skill Levels, Learning Curves &

PrioritiesKnow your people

Know your priorities

Task Duration EstimationPERT Method

(a + 4b + c) / 6

PERT MethodDocument the estimation process

Delphi MethodWAG and SWAG

The Psychology of Task Durations

10 days to do 5 days of work. Why?

The Psychology of Task Durations

Work seems to expand if we have time for it

The Psychology of Task Durations

Do it tomorrow

The Psychology of Task Durations

Padding – we can’t seem to win either way

The Psychology of Task Durations

It seems for many it is natural to keep working until we are out of time or late

Practical Time Estimating

We must pad or buffer

We must be realistic

Where’s the balance?

Practical Time Estimating

There are methods that are tried and true

Practical Time Estimating

Technique Example 1

Practical Time Estimating

Technique Example 2

Practical Time Estimating

Technique Example 3

Practical Time Estimating

Technique Example 4

Develop consistency in estimating

Follow standards

Key factors in achieving project success

Know your objectives and these will drive your approach to Task Duration Estimations

Estimating Task Durations

Standards

Documentation

Communication