Estimating time and cost for a project, or even part of a project, can be tricky.  Breaking down the tasks into subparts must be done or you don’t stand a chance.  Given enough time, you can develop an accurate estimate and put a good plan in place.  But sometimes you can’t flush out all the contingencies because you’re under pressure to provide ‘your best guess’ RIGHT NOW, and we all know how those rough estimates suddenly become etched in stone.

You don’t want to give an estimate that is too low because you risk the possibility of project delays and cost overruns when unexpected problems arise.  You don’t want to give an estimate that is too high because you risk the project not moving forward due to inflated costs.  There is a fine line to giving a ‘close enough’ estimate within the time constraints you have.  Even when giving quick estimates, some allowance for potential problems and risks must be made.  This is especially true when you don’t have much time to think about it.  By keeping a checklist of past problems and risks, you can quickly refer to the key areas that got you into trouble before and are likely to affect this project.

 Some items to include:

• new tools or test equipment being used;
• current staff workloads and distractions;
• contractor or employee training needs;
• any changes in current work procedures or instructions;
• critical functional areas that need more attention or definition;
• project documentation generation and reviews, especially product requirements;
• verification reviews, especially traceability between requirements and test plans;
• software unit testing and metrics;
• user and safety manuals;
• test lab time and cost;
• agency audit efforts;

If history shows it takes twice as long to finish tasks than you think, you could shortcut the process and just double your quick estimate. Or you might add extra time since you know the managers will try to trim it back anyway. Just ‘winging it’ in this way may get a quicker answer, but using a more systematic approach to the estimate process will give you better support for your assumptions. If you still don’t feel comfortable with the estimate, you should try to ask for more time to provide it and use your checklist as ammunition of things that need to be considered. At a minimum, get more clarification about how the estimate will be used. Just as with functional safety designs, taking time to assess the risks and consequences of non-ideal and unexpected conditions can go a long way to improving project estimates.