The following article was found on a http://mondo-technology.com/.

One of the really big problems in the engineering world is estimating the difficulty, time, and cost of a new project. In many cases, estimating the project is far more work than actually doing it. Here is one way to get a handle on how much trouble any specific project may be.

First, divide the whole project into parts. If needed, divide the parts into smaller parts until you can put each of them into one of the following categories:

Class I – Something you have already done successfully.

Class II – Something that has already been done by others and documented.

Class III – Something that has been done by others, but not documented.

Class IV – Something no one appears to have ever done.

Class V – Something that is generally considered not possible.

Class VI – Something that violates established laws of physics.

The overall class of a project is the highest number of any of its component parts. If you have just one Class IV part, the project itself is considered Class IV.

If your parts are all Class I, no problem. Just cobble together all the bits and pieces from previous projects.

Class II means you do some research into how it has been done before. Google around and see what you can find that fits what you need.

Class III is where it begins to get sticky. You will have to 'reinvent the wheel' to do this part, but you have reason to believe it is possible.

You can be in trouble estimating the project if you have any Class IV parts. If you do, work on these first to see if any of these parts are a deal killer. Let your client know that until you determine if this part is possible, you really don't know about how much total effort the whole project will take.

Unless you are engaged in pure research for a University or something, don't do any project with a Class V item.

Class VI means you avoid the project entirely.