Bottom Up Estimating - Need clarity please

suiii's picture

Hello Experts,

I wanted to know if "Bottom Up Estimation" can be used for Estimate Activity Durations? and if no, why not?

I was going through PMBOK and they mention that Bottom Up Estimation is a tool for Estimate Activity Resources and Estimate Costs.

So, not clear as to why this tool cannot be used for Estimate Activity Durations?

Please help clarify.

Thank you,

Regards,

Suiii

 

 

 

 

admin's picture

It can be used for Estimating activity durations also. Practically speaking if you have a project with few activities you can determine the duration of each activity and sum it up for bottom's up estimation. 

Typically the accuracy will be more if you have done similar work in past. Otherwise its a time consuming process to estimate bottom's up due to level of detail involved 

suiii's picture

Thank you so much,

Regards,

Suiii

 

This activity would not be performed by the PM alone, you don't need to be the expert on everything.

For example if the work package was to build a web page and joe was assigned, you would sit down with joe and look at the requirements and ask his opinion on how long he thinks he would take to build it. There are other means but consulting the expert would be PMI's preferred methodology. If joe says 4 weeks you may add a +/- factor as PMI like to do.