In each of the following scenarios for planning Steve and Susan’s wedding determine which of the five activity resource estimation tools and techniques is being used.
Sally has to figure out what to do for the music at Steve and Susan’s wedding. She considers using a DJ, a rock band, or a string quartet.
Alternative analysis.
The latest issue of Wedding Planner’s Journal has an article on working with caterers. It includes a table that shows how many waiters work with varied guest-list sizes.
Published estimating data.
There’s a national wedding consultant who specializes in Caribbean themed weddings. Sally gets in touch with her to ask about menu options.
Expert judgment.
Sally downloads and fills out a specialized spreadsheet that a project manager developed to help with wedding planning.
Project management software.
There’s so much work that has to be done to set up the reception hall that Sally has to break it down into five different activities in order to assign jobs.
Bottom-up estimating
Sally asks Steve and Susan to visit several different caterers and sample various potential items for the menu.
Alternative analysis
Sally calls up her friend who knows specifics of the various venues in their area for advice on which one would work best.
Expert judgment.
Estimating activity durations
Once you’re done with activity resource estimating , you’ve got everything you need to figure out how long each activity will take. That’s done in a process called activity duration estimating . This is where you look at each activity in the activity list, consider the scope and the resources and estimate how long it will take to perform.
Estimating the duration of an activity means starting with the information you have about that activity and the resources that are assigned to it, and then working with the project team to come up with an estimate. Most of the time you’ll start with a rough estimate and then refine it to make it more accurate. You’ll use these five tools and techniques to create the most accurate estimates:
- Expert judgment will come from your project team members who are familiar with the work that has to be done. If you don’t get their opinion, then there’s a huge risk that your estimates will be wrong.
- Analogous estimating is when you look at activities from previous projects that were similar to this one and look at how long it took to do similar work before. But this only works if the activities and the project team are similar!
- Parametric estimating means plugging data about your project into a formula, spreadsheet, database, or computer program that comes up with an estimate. The software or formula that you use for parametric estimating is built on a database of actual durations from past projects.
- Three-point estimates are when you come up with three numbers: a realistic estimate that’s most likely to occur, an optimistic one that represents the best-case scenario, and a pessimistic one that represents the worst-case scenario. The final estimate is the average.
- Reserve analysis means adding extra time to the schedule (called a contingency reserve or a buffer) to account for extra risk.