So I am doing a feasibility study for my PhD and have to design and then deliver an intervention to a group of parents. My supervisor wrote the bid for which we received the grant. He seems to think that what he wrote in the initial bid is the only way to go (making me sometimes feel like a research assistant but that is another issue). After 7 months of lit review, talking to key stakeholders etc it seems that his proposed idea of 16 people in an intervention group with just me as the facilitator is not quite a good idea ( politely) - everything and everyone suggest groups of 7. He just won't listen to me or the research and said there is no evidence to suggest the opposite... I seriously don't know how I am going to do it but also feel it is MY phd and I feel I constantly have to do things that were his idea.. . I know I am in receipt of a scholarship but I find it hard to deal with this. ANy advice on dealing with a stubborn supervisor or even better to suggest that group sizes over 7 are a bad bad idea.....?

It is very difficult once you are in the PhD to do anything about this - especially when you have just started.
What makes you think you are correct and your supervisor is wrong by the way?
Your supervisor is much more experienced than you are. Be very certain you are correct before you go any further.
I would probably allow the first project to slide the supervisors way and then I would tell them that I wanted to now try entirely my own idea next with the supervisor offering nothing more than advice. That might be a good compromise. You presumably have plenty of time to develop your own voice.

Your post is an important one though and a subject which has been raised many times.

For the benefit of other potential PhD students I would like to offer some advice. It is absolutely crucial that when you interview for PhD positions that you recognise your own value and worth. You simply MUST interview the supervisor. Find out what they expect from you in terms of autonomy, working hours, location, who writes the papers, who comes up with the ideas. This situation is easily avoided by having that conversation up front. Disaster can ensue if you avoid it.

Thank you very much for your detailed response. I am not saying " I am right" - I just feel I need to search the literature to back up his ideas but the literature doesn't... I told him in a nice way but he is stubborn and laughs it off. He is very nice but it makes me feel I have to find what he wants me to find..

He sounds like a bit of a XXXX. Do you have another supervisor who you can chat to about it, or another student who also has/had him as a supervisor? I think if the literature support your view and not his then you should pursue it with him - not in an emotive way but just with the facts of the matter. Ask him specifically what the advantages of 16 are over 7?

You're unlikely to win with these type of people. If I pushed my supervisor on this he would say 'go ahead, do it with 7, but when your paper gets rejected or you get a revise and resubmit on your PhD, you know who to blame'.

Sometimes it's easier just to go along with what they say; pick your battles carefully. I've found it's better to keep them sweet in order to reap future benefits of their advice/connections/whatever than start annoying them and souring the relationship.

Like pm133 said, you will likely have other opportunities to go your own way later in the PhD.

Good advice. I am dealing with something similar at the mo - and probably just going to do it for all the extra work even though I think it is pointless.

Hi there, my experience with supervisors is that when they are 'sticking to their guns' about a matter, then that is what usually occurs. It is your PhD, although you mentioned a grant which was obtained by the supervisor. Your supervisor's perception might be that while it is his name and reputation at stake on the grant application, then he would prefer that his structures and sample sizes are adhered to.

Do you think that sample size might be important here for the findings? Or perhaps that is behind your supervisor's thinking? If this is the case, is there a problem with having two groups of 7-8 for delivery of the intervention? (It may be that people drop out as well or have an inconsistent attendance pattern, so perhaps this is why he is thinking of 16).

When you talk to him about this, what does he say about the research that you provide as evidence for your claim? Does he read it or acknowledge any of your arguments?

Sorry, it is a pain. I have a couple of very good supervisors and the second supervisor is stubborn, experienced and set in her ways, very thorough and very busy. It causes me some frustration as I have to wait for ages for feedback and I have to follow most of it as she won't sign me off unless I do. I haven't found a way to change this though and have had to just be patient. My Masters supervisor was exactly the same. In the end I wanted to complete and pass my theses and had to go along with their processes.

The funder has funded the research based on what was written in the grant application. The funder may well have not wanted to fund something with smaller groups.

You are conducting a feasibility study- larger groups presumably make sense from a cost-effectiveness perspective.
If everyone else has done smaller groups and it was feasible, there would be no value in doing a feasibility study.

I certainly understand how you feel. Part of the process is gradually becoming more independent. Don't be in a rush unless this is a red line issue for you: you could completely screw your PhD if you are too impatient to get your own way.

I found myself in a situation similar to this when trying to submit a collaborative paper. The lead PI from the other group caused some problems by taking an approach I didn't agree with. Only when the paper was ruthlessly rejected and he had run out of ideas did he come to me for help. My help consisted in exactly the same suggestions he had rejected several months before - verbatim! The paper was accepted within a week of resubmission with my changes in it. I have honestly never seen a desperate man so grateful. I never had a problem with him after that.
Sometimes you need to let arrogant people fall on their faces once or twice. Just make sure that when it happens, you are there to help out without grinding their face in the mud.
A very useful life lesson for me proving you are never too old to learn.

I should add though that just as I was beginning to think the sun shone from my backside, I had another paper of my own rejected with comments so offensive that I had to wait 6 weeks before I calmed down enough to fix them. That still hasn't been accepted for publication yet. Can't wait to see how that turns out. Hubris affects us all. Be careful what you wish for :-D