How to know that a project schedule is realistic?

Question

I always shoot myself in the foot when I schedule a project, as all my project schedules so far are unrealistic (I'm still an inexperienced project manager). So my question is to the experienced project managers out there, how do you know (prior to executing the project) that your project schedule is realistic? Do you use any metrics to determine this or do you just follow your hunch?

Answer 1

The key to a great schedule, besides really understanding the requirements and breaking them down into smaller work packages, is to have really good estimates. The estimates are better if:

- there are multiple estimators
- estimates are done bottom up (detailed) and top down (metrics and rules of thumb)
- the estimates are independently checked

I do use metrics, however am only familiar with those of software projects.  If these are your projects, look for books by Fred Brooks (The Mythical Man Month), Gerald Weinberg (The Psychology of Computer Programming) and Ben Shneiderman (I believe the title is Software Metrics - he published studies at the University of Maryland) for some great tips.  The metrics and rules of thumb will vary by industry.