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The question is divided into two parts and related to the situation like: Committee gets PhD thesis to read through/give comments/report on it. Thesis is written based on several publications. 1. What is the chance that Committee members are going through the papers as well as the thesis? For the purpose of comparing/so on...?

2.I am wondering because if they would find that some information which was published looks different in your thesis (reevaluated or even corrected because in the paper there was not-fully-correct data)...how will defense then go and how to turn it to a safe ground? (P.S. corrections which do not change the main idea and conclusions are still the same. As an example it can be like you corrected the background of your signal in one way for publication,then you realized that it was rather stupid and corrected it in different way. Signal is still there, interpreted the same, but qualitatively Figure looks different.)

Thank you for your answers!

  • It may well be that some committee members have already read some of the papers. – Dirk Aug 31 at 12:34
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I think that many, though not all, committee members will try to do a good job, but they may fail. My perspective is mathematics in which a dissertation is very arcane (or can be, anyway) and few people in the world are as well versed in the particular tiny research area as the author, and, perhaps, the advisor. It may be a bit different in some other fields and perhaps wildly different in dissimilar fields.

But people are also busy with their own work and don't have the time or the inclination to learn every part of the background of a given (math) thesis. Many will try to read it, but will get stuck at some point. Questions from those people are likely to be to ask for some explanation of what is going on at the point that they got stuck. If you know your work well, these are fairly easy to answer, though it is possible to give an unsatisfactory, overly pedantic, answer. If you can provide insight about how to continue then you get a win.

But many people, being busy, will just defer to your advisor. This is especially the case if your advisor is a well respected mathematician. A couple of days (maybe hours) before the oral exam, they will go the the advisor and ask: "This is ok, right?". The advisor will assure them that all is well and so they have the confidence to sign off on your work. Proof by Authority, I suppose.

If you think this is cynical, then ask around. I know that it happens, both from being a student and from being an advisor. I won't admit, of course, to that behavior when I was another committee member.

However, as Bryan Krause says, things differ. You may get an eager committee member who has examined your work in detail. If they disagree with it or have a certain sort of personality, you might get uncomfortable questions. You need to give reasonable answers, of course, but you can, I hope also depend on your advisor to serve as your shield from overly critical things. You won't be required to give a perfect answer to every question, but need to demonstrate mastery of the ideas in the thesis and the surrounding micro-field.

But, in particular, you can't be expected to give snap answers to questions that require study and reflection to properly answer. If someone has seen a paper that you don't know about and it seems to say something different from what you have written, then it may take a lot of analysis to see (a) whether there really is a difference and (b) why the different results arose.

My committee was something like the following. My advisor knew everything that I did and he supported the work. Another faculty member was in the same research group and understood it well, but had few questions. But he had the background to follow it without a lot of detail. Another one, I think, just deferred to my advisor. Another who didn't ask questions in the "defense" came to me afterwards and admitted that he couldn't understand it very well (his sub field was different) but he found a few typos and gave me a list.

On the other hand, I heard of a case at the time, possibly apocryphal, in which a candidate in chemistry was denied a degree because the talk mentioned ph throughout. In that place, an external (out of field) examiner was required and that person asked for a lay-person's explanation of ph. The candidate froze up and couldn't answer, though it is a subject studied in first year chemistry. But, the fact that such a story was remembered (or made up) points out how rare such things really are.

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  1. What is the chance that Committee members are going through the papers as well as the thesis?

This of course depends on the specific committee members...some may take their jobs more seriously and read in a lot of depth; others may mostly trust the thesis advisor to do that job and simply verify that enough effort has been put in to grant the degree.

As an example it can be like you corrected the background of your signal in one way for publication,then you realized that it was rather stupid and corrected it in different way. Signal is still there, interpreted the same, but qualitatively Figure looks different.)

You should be prepared to explain differences like this at your defense. I might not suggest calling your work "stupid" (although, I would have felt completely comfortable describing it as such to the people on my own committee who were somehow both excellent scientists and living human beings) but research is typically an iterative process. If you changed part of your process at some time during your work, hopefully you did so for a good reason, and you are (hopefully) the best expert in your own work, and you understand and can explain your reasoning better than anyone else.

Adding in the appropriate details:

Signal is still there, interpreted the same, but qualitatively Figure looks different.

is exactly the type of explanation your committee will want to hear at a defense.

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