What should be the main point to keep in mind when estimating the time for Research and Development task. Suppose I have to estimate "ABC" task using "WPF" technology and I have no experience for it, I need to some R&D for it.
You could take a guess as to how long you think it'll take you to research the new technology and then how long it'll take for you to do the development and multiply that by two. Of course that's pretty fluffy, but usually anything involving estimating a task is pretty fluffy (well, at least I don't like to). There are so many factors involved when estimating: whether it be dealing with new technologies that could be take longer than you think, usually it involves dealing with code written by other people which could add an 'x' factor of complexity to what should be a simple task.
Usually when estimating time, it's always best to at least have a general 'spike' where you sit (whether it be by yourself, or even better with some other team member) and have a play for an hour or two (or however long you choose). This at least gives you a bit of time to have better context with what you're dealing with. When looking at the new technology, perhaps read a bit of the doco, read and play with a 'getting started' guide etc. Then when you go back to the estimation table, you will have a better idea with what you're dealing with.
The best way to approach it is consult with someone who has been there already. His experience plus general idea of of good he is compare to your staff should give you a fair estimation.
The older the technology is - the more experienced people there will be around and more places on the web to find answer to question.
If you're researching something brand new... the data sources should be limited and I will take any estimation, and double it....
Don't give an estimate until you have had time to play with the technology. Allocate a certain time (2 days, 1 week, whatever you can get from management) to understand the concepts and write some code yourself with it, to get a sense for what the development process takes and how steep the learning curve is. Then, estimate.
Ideally, one should not give an estimate without solid evidence. After all, an estimate is a probability, and probabilities are mathematically significant figures, not gut feelings pulled off thin air. (See "Software Estimation" by Steve McConnell for more on this.)
Unfortunately, too often we are required to provide estimates on tasks for which we have a great deal of uncertainty about the technologies that will be involved. This is the case, for example, of government grants and other non-technical scenarios. In these cases, and being pragmatic, it is good to provide an estimate even when we are not familiar with the technologies.
Techniques that I often use include uncertainty cones and timeboxed development.
Hope this helps.
Pure Research Projects
Set a time or resource cap in addition to a number of interim milestones / reviews, to re-evaluate whether you can afford to continue. Ideally before embarking on the research you will have a good idea of potential benefits of succeeding. You might also want to define different grades of success and a contigency plan in case the effort will not come to fruition, before you start.
Spiral model of development will come handy.
Applying Existing Technology to a Problem
For current mainstream technologies such as WPF you might try to find out how long would it take for someone with comparable experience to learn the technology. Evidence might be collected from other people experience and available training courses.
For non-current or niche technologies you might be better off hiring a consultant or sub-contracting the job (bear in mind the difference between consultant and contractor).
Grade the project on
Keeping Status Quo - Bug Fixing - Enhancement - New Functionality - New Product - Revolutionary
scale. Each position on the scale will usually mean a factor of 2..5 of risk and effort increase. Having a reference point which is to say if it normally takes 2 days in your organisation end-to-end to fix a bug, you can gauge that an enhancement will take two to five times longer, anything between 4 to 10 days, of course coding will only be a small proportion of the this effort.