I find it surprising how often I end up reinventing the wheel when it comes to project estimation. I suspect that there are others out there who end up doing the same, and so I decided that it was past time that I standardised my personal approach to project estimation using a model spreadsheet. Approaches and standards for estimation vary, but my preferred approach to a second cut estimate is:
- Work out the set of scenarios that apply to the project being built.
- Estimate each using a complexity rating (High, Medium, Low etc.).
- Adjust this according to how complex the project is likely to be.
- Use this to work out the likely number of man-days that the project is likely to take, based on appropriate experience and best-guesses.
- Map this to an effort estimate, and hence to a likely team size and duration.
It is this approach that I have implemented as a spreadsheet model for future, and general, use. The spreadsheet is available for download here:
Over a series of posts I will document the usage of the model, how it calculates its figures, the reason behind its structure, and slowly work through an example of the usage of the model. The model is intended to be easy to use and widely applicable. Please feel free to use it, and give me feedback about it. Leave a comment, call me on +44 7887 536 083 or email me at firstname.lastname@example.org.