First, what follows is the opinion of a current Ph.D candidate in a Canadian University and who is nearing the end of the Ph.D process.

Second, I'm not really sure about what you mean by 'critical region' and 'success or failure'. By critical region, do you mean a part of the PhD process? By 'success or failure' do you mean getting to the defense and being awarded the diploma vs quitting? Or is success related to having impact with your research or being cited? Or is success related to getting a job in a research institution based on your past research? I think your question would benefit from being clarified.

If by 'critcal region', you meant part of the Ph.D process and success only entails getting your diploma, my personal belief is that the most critical part actually occurs before you start your Ph.D. One really needs to realize that this is going to be a long, hard and tedious process in a quite competitive environment and for which the professional benefits are not as clear as they are for the Bachelor's degree or the Master's degree. Some say a Ph.D might even be a nuisance if in the end you cannot or do not want to work in research. However, if you do want to work in research, some say a Ph.D is not enough. So for me the first critical step is to ask yourself: 'Do I really, really, really want to do this?' Having the support of your family and other half is also a good thing.

If you answered yes, the next critical step is to find a research topic that is very stimulating to you. You are going to be living this research topic for every day and night for the next 3-6 years so you'd better be sure you'll like it as much as you can (and like other things you love and live with, the relationship may still be hard to live with on a daily basis).

Then, you need to find a research adviser who will be supportive (intellectually and financially perhaps), stimulating and possibly the hardest part, available.

I think that if you've managed these steps, you are in a good position to go through your Ph.D.

May be one last comment. If I refer to my personal experience, it is very important to stay aware of potential alternative research questions that arise during your Ph.D process. Some of them might end up being more fruitful and sometimes bear more low hanging fruits than your original research question. Sometimes, it may result in an 'easy' additional publication. Or it can plainly save you in the case you end up realizing that your initial research question is a dead end, which happens you know...

Best regards,

Laurent

Thank you, Laurent Cormier,  for input.

Actually, I just wanted to have input why students are unable to complete their PhD even after knowing all these problems in the very beginning?

More specifically, one can not blame any body why did he start then? there must be number of critical point or points ( region ) because of which they become frustrated and they quit. i want to tap this critical point.

Best regards

Rafique

Dear Laurent Cormier ,

your argument regarding topic and supervisor selection weighs high. A good point high lighted by you. 

Regards

Rafique

Hi Mr Rafique,

To begin, please excuse me for the replicated (and long) posts. This morning, the website would not accept my answer, which I tried to submit a few times. When I came back later, my answer was still not showing so I reposted it. Now, it seems that it appears many times. I have deleted the replicates.

As for reasons to quit after the Ph.D is started, I can see a few. A first one is that, for some people, academic research is just not the right path and they needed to have a taste of it to realize they took the wrong turn. To me, someone in this situation wins more by quitting and finding a more suitable journey than by sticking to the Ph.D.

Another evident reason lies in the fact that most grants only last three years while the average Ph.D length is often longer than that. This is perceived by some as a motivator to the quick resolution of the Ph.D process, but even if one works hard, there is no assurance that three years will suffice. Since Ph.D students often already have a good set of professional qualifications, it might be tempting for the student to take on a full time job towards the end of the Ph.D in order to raise some money and meet they ever increasing financial needs. However, as Ph.D research requires a full commitment from the student, working full time might very well lead to the loss of momentum in the research effort and in the abandon of the research. I've seen this happen to a few friends.

In therms of critical points, I guess many Ph.D end up facing the fact that there are already some pretty good answers to the research question they had in mind. If this happens late in the Ph.D process and if one did not remain aware of other potential avenues that are closely (or remotely) related to the original question, it might be too hard to cope with and quitting appears as an option.

Not to mention industrial partnerships that keep on changing the research question.

Or realizing that the answer to the question you asked yourself when you were at the undergraduate level (Has your professor had always been 'like that'?) was: No the Ph.D made him like that.

And so on...

Regards,

Laurent