So let's say I have a problem (X) that needs to be solved. Most people in research use several approaches around a sub-topic Y. Most of these algorithms have performance of 80-95% accuracy so there is a space for improvement. I understand that a proper PhD topic would be to find a better solution here.
But what if I just use a new technique (K) to solve this problem? It hasn't been addressed yet in literature. I expect the performance of it to be lower or near the conventional methods. I justify using it because it's outperforming in imagery tasks and it would open up the literature to a new method.
If I use K to solve this problem and get lower performance than conventional solutions Y, does that count as a proper PhD thesis?
In other words, to define a PhD topic, should I find the problem to solve or use a tool and see how it solves a problem?
Here are my couple of rules that worked for me, students and friends:
What can you publish?: Find an area/sub area first, not the specific topic until you have a publication. For example, I choose the area of code generation, I keep working on it and then when I'm collecting my thoughts and findings to write a publication, I need to put a title on it. That title of the paper becomes my title, lets say: a code generator for the domain of X. If I can't publish more then well that will be my PhD thesis title. However if I keep working on it and then come up with more publications then that would effect my title as well. You see what I'm trying to say here?
Tools: The rule of thumb is that research-based tools developed by researchers are not that good in general. Their quality of code is not that great, and if you put all of your eggs in their basket, then you are risking many things, like time, effort and so on. However, if the tool is developed in your research group so then you can trust it to some extent, because then you can talk to the creators if you hit a problem.
Passion and Problem Not X and Problem: Find a problem that you are passionate about, that you will work couple of years on it; so why not something that you like or love? You did your Bsc and Msc, what topic/problem made you mad? What problem you saw that you think you can solve? Finding an easy path to a problem ends in disaster. You will talk about your problem/solution to other researchers, don't be a lifeless researcher that just roams around and have no passion about his/her topic. Again, you see what I'm saying here?