6 4 Estimate Activity Duration The process of

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 Monitor • Occurs during the Planning Phase Initiation Planning Execution Close Control Adapted from PMBOK 4 th Edition BSBPMG 503 A Manage Project Time

6. 4 Estimate Activity Duration • Inputs to Estimate Activity Duration ü Activity list and attributes ü Activity Resource requirements and estimates ü Resource Calendars ü Project Scope Statement ü Productivity metrics and estimating data • Tools and techniques to Estimate Activity Duration Analogous Estimating Parametric Estimating Three-Point Estimating Expert Judgement Reserve Analysis Adapted from PMBOK 4 th Edition BSBPMG 503 A Manage Project Time

6. 4 Estimate Activity Duration • Analogous Estimating ü Develops duration estimates based on previous projects with similar size, risk and complexity ü Relies heavily of expert judgement and previous experience ü Less costly and less time consuming than other methods ü Least accurate ü Most common form of duration estimating • Parametric Estimating ü Duration is quantified by multiplying the quantity of work by Monitor the labour hours required ü Relies on published estimating data ü Common in Construction Initiation Planning Execution Close Control Adapted from PMBOK 4 th Edition BSBPMG 503 A Manage Project Time

6. 4 Estimate Activity Duration • Three-Point Estimates - PERT ü Calculates the Expected activity duration based on the weighted average of the Most Likely, Optimistic and Pessimistic estimates ü Often more accurate than other methods and quantified range of uncertainty • Reserve Analysis ü Inclusion of contingency ü Can be calculated for each activity ü Can be calculated for entire project Monitor Initiation ü Often a percentage based on risk or complexity Planning Execution Close Control Adapted from PMBOK 4 th Edition BSBPMG 503 A Manage Project Time

6. 4 Estimate Activity Duration • The major output of this process ü Activity Duration Estimates ü 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 ü 2 weeks +/- 2 days – the activity could take between 8 and 12 days ü 3 weeks +/- 30% - the activity could take between 2 weeks Monitor and 4 weeks Initiation Planning Execution Close Control Adapted from PMBOK 4 th Edition BSBPMG 503 A Manage Project Time