Attached is an Excel spreadsheet that will help you estimate how long a software development project will take to complete by decomposition. The formulas used are taken from Steve McConnell’s amazing book on Software Estimation.
Click Here to download the spreadsheet. Better yet, right-click, choose ‘Save Target As…’, and save it as an .xsl file. I can’t upload Excel files to the blog, so it has a .txt extension.
Here’s a brief description each worksheet in the spreadsheet:
Tasks
- Enter the name of each task, along with a best case, most likely case, and worst case estimate. An expected case estimate will be calculated for you. This number weidhts the expected case by a factor of 4.
- As you work on the project, enter actuals into the “Actual Outcome” column. As you do this, the “>10 Tasks” column will compute standard deviation based on whether your actuals are within the estimated range.
Summary
- Used to perform further estimation calculations. Some of the fields will show the #DIV/0 error until you begin to enter acutals in the Tasks worksheet.
Conclusion
- Best and worst case estimates (based on the expected case), and 50% and 90% confident estimates.
Summary – 10 Tasks
-
- Same as “Summary” worksheet, but look at these #s if there are only 10 tasks in the Tasks worksheet.
Conclusion – 10 Tasks
- Same as “Conclusion” worksheet, but look at these #s if there are only 10 tasks in the Tasks worksheet.
