Estimating enhancement requests before requirements have been gathered

I work in a software development department that develops and maintains in house software for the organisation we are part of.

There is a process where business users can submit requests for enhancements to any of in-house developed solutions. The user fills in a template and submits it to email group for an estimate to be done.

The problem I have is that we are expected to provide an estima开发者_如何学Gote based on the information supplied by the user. The level of detail contained in these requests is usually very light. There is no filtering of these requests before they reach the "Estimates Forum", and there is no quality control on them either. The people responsible for providing estimates are developers who are all working on current projects and enhancements.

My question is how are enhancement requests handled at other internal software development departments? Or, does anyone know of a "best practice" approach for this problem?

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The best you can do is to provide them with a minimum and maximum range which you revise as you get more information. Make sure the range is large enough to include the final estimate though.

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Keep 2 iterations. The first one with a +/- 20% variance (almost always + ) and then based on feedback or final requirements, further analysis etc you take more time to get back with the final estimates which are more accurate.

If it's developers estimating, the general tendency is to under estimate (it's always 2 days time) - so then add a buffer on top.