Are there any studies that confirm or deny an effect of titles one has (university degrees > undergraduate or peerages where they still exist) to the chance of being elected?
At the presidential level in the United States it is certainly true that a college degree has become effectively mandatory for candidates. In total, only 10 Presidents did not graduate from college at all, and Harry Truman is the only such example after the 19th century.
However, that does not seem to imply that title bearing degrees past an undergraduate level have proven beneficial in the United States. Only 6 Presidents received law degrees, only George W. Bush has an MBA and Woodrow Wilson was the only Ph.D. to become President.
In Congress, the trend is very similar and in the 111th Congress a full 95% of the members had some level of educational degree. In Congress it seems that the education level is marginally higher than for our Presidents with most holding at least a masters degree. In fact, roughly 40% had a law degree and another 20% had some type of masters degree. Only 23 members of the House of Representatives were Ph.D. recipients however.
From this evidence, it appears that on average Americans prefer a candidate with some level of education past high school, but that a title or specific specialization is not important to them.