• An estimate is really just a guess.

• Yet, we have to negotiate expectations for accuracy.

• I’ll check in the unit tests by noon
• I’ll have the search feature implemented by Friday
• We will have the project done in December

• Why do we need to estimate?

• We need to set expectations
• We need to allocate time and resources
• Other tasks depending on its completion
• We need to make better estimates in the future

• Effort can be structured based on the visibility of results.

• Tasks – an effort that produces an identifiable and valuable output
• Activities – a sequence of tasks 
• Projects – a complex sequence of activities

• Estimation with any accuracy gets increasingly hard, perhaps impossible for certain processes.

• Complex projects
• Changes in requirements or resources
• Innovation

• Projects are seen to fail or succeed based on the accuracy of the initial estimates.

• Comparison– this task is similar to another task I completed

• Ranking – this task is harder (or easier) than another task

• Coercion– we are told how long a task will take

• Time-boxing – I can allocate only this amount of time

• We often neglect our experience in estimating tasks.

• Estimates express ‘ideal’ time and effort
• Communication
• Meetings
• Set up and tear-down