Is excluding some parts of proposal in Phd. dissertation acceptable?

Question

Is this situation considered acceptable, wherein a PhD. student has submitted a research proposal for evaluation and the proposal is approved by committee members, but due to some reasons (which are actually admissible) the possibility of conducting some part of what is mentioned in the proposal is quite out of reach in practice (it was realized after a series of experiments proved that doing this part of proposal in practice is not possible),so student decides to remove a part of the proposal in their dissertation?

If yes, does this have to be mentioned in the dissertation? Can it have bad impacts at the dissertation defense?

Answer 1

It might depend on where you are doing the PhD, but, as far as I was/am concerned, it should not matter. The proposal is written at the beginning of a PhD project and, as such, many things can change which have a serious impact on your ability to do what you originally suggested. I think everyone knows that you have to just go where the research takes you—if you find that you proposed something that turned out to be impossible, that is just how it is.

Also, unless things are done very differently in your country than mine, your examiners will never see your proposal, they will only ever see your thesis; they will never know what you intended to do at the beginning of your project, and will only care about what you accomplished by the end of it.

So, assuming your supervisor and your graduate research school (or whatever department handles the PhD students at your university) are happy with your progress, there should be no problems.

However, you will only know how much it matters for sure if you ask your supervisor, because random people on the internet cannot give you any reliable advice.

Answer 2

This depends very much on the customs and regulations of your institution.

In general, Ph.D. quality research cannot be planned ahead and it is understood that the outcome can be quite different from what was anticipated when the Ph. D. proposal was submitted and defended.

In general, it is the job of the Ph.D. advisor to interact with the student in order to guide them exactly on issues like this. It could be that in your institution, the committee is taken this place. My expectation as a Ph.D. advisor would be that I would be informed and asked for advice when the direction of the thesis changes dramatically. One important aspect of leaving out parts of the work is that what remains might no longer fulfill the requirements of a Ph.D. thesis.

To summarize: The proposal and the Ph.D. thesis are often very different. However, there should be guidance provided for these changes. If guidance is not sought, the Ph.D. student might find themselves with insufficient work for a Ph.D. Besides, it is the advisor's responsibility to guide the student.

It is hard for me to imagine a situation where a student would present a thesis for approval without interaction with the advisor (or who-ever or what-ever takes the advisor's place).