Supreme Court nominees present themselves one way at confirmation hearings but act differently on the court. That makes it difficult for senators to cast informed votes or for the public to play a meaningful role in the process.
The study — with the unwieldy title "An Empirical Analysis of the Confirmation Hearings of the Justices of the Rehnquist Natural Court" — published in Constitutional Commentary, looked at how nine long-serving justices answered Senate questions, and how they then voted on the court. While it does not say that any nominee was intentionally misleading, it still found a wide gap.
Justices Antonin Scalia and Clarence Thomas, for example, told the Senate that they had strong respect for Supreme Court precedents. On the court they were the justices most likely to vote to overturn those precedents. Justice David Souter deferred more to precedent than his Senate testimony suggested he would....
Well, I looked at the study, and I'm not sure I'm quite persuaded by how it categorizes the data. In particular, it seems to me that (according to the testimony reported in the Appendix, quoted below), Justice Scalia generally said that he had strong respect for old precedent -- and my impressionistic sense is that Justice Scalia has acted precisely this way. Justice Thomas, for instance, wrote a separate opinion in favor of overruling the Court's 1798 Ex Post Facto Clause decision in Calder v. Bull; Justice Scalia did not join that. The great bulk of Justice Scalia's votes in favor of reversing precedent have focused on precedent from the past several decades (unsurprising, partly because there's a lot more newer precedent, and partly because Justice Scalia is indeed big on tradition). So I see no "wide gap."
Here's the testimony from the Appendix:
Scalia: Stare Decisis/Precedent
 The Supreme Court is bound to its earlier decisions by the doctrine of stare decisis in which I strongly believe.
 Q: Well, what weight do you give the precedents of the Supreme Court? A: It depends upon the nature of the precedent, the nature of the issue. Let us assume that somebody runs in from Princeton University, and on the basis of the latest historical research, he or she has discovered a lost document which shows that it was never intended that the Supreme Court should have the authority to declare a statute unconstitutional. I would not necessarily reverse Marbury v. Madison on the basis of something like that. To some extent, Government even at the Supreme Court level is a practical exercise. There are some things that are done, and when they are done, they are done and you move on. Now, which of those you think are so woven in the fabric of law that mistakes made are too late to correct, and which are not, that is a difficult question to answer. It can only be answered in the context of a particular case, and I do not think I should answer anything in the context of a particular case.
 Q: [A Supreme Court Justice] said that a precedent might be less authoritative if it had stood for a shorter period of time or if it was a decision by a sharply divide court.... Would you agree with that general sentiment? A: Well, I think the length of time is a considerably important factor. The Marbury v. Madison example that I gave in response to [a previous question.] I am not sure that I agree with [the Justice] that the closeness of the prior decision makes that much difference. I mean, if Marbury v. Madison had been 5 to 4, I am not sure I would reverse it today. But I can understand how some judges might consider that that is an appropriate factor as well. I agree — I certainly agree with the former. The latter would not have occurred to me, but maybe.
 I agree with the statement that longstanding cases are more difficult to overrule than recent cases.... [A]s I've said, some cases that are so old, even if you waived a document in my face proving that they were wrong when decided in 1803, I think you'd have to say, sorry, too late.
This is one highly general and banal pro-precedent statement ("The Supreme Court is bound to its earlier decisions by the doctrine of stare decisis in which I strongly believe," which is surely true, given that in the overwhelming majority of cases all Justices follow stare decisis simply for pragmatic reasons), followed by three statements expressing respect for old precedent. I wouldn't count this testimony as strongly pro-precedent in any absolute way; and I don't quite see how one can sensibly compare it to the other Justices' statements on precedent, which is what the study purported to do.
If each statement could be fairly boiled down to a simple "for precedent" or "against precedent," then maybe such comparisons could be made (though I doubt it). But if I'm right that Justice Scalia's statements were far from such simple assertions, and instead distinguished different kinds of precedents, then I don't see how the survey can sensibly give Justice Scalia a high pro-precedent score. (Justice Thomas's statements are likewise hard to categorize as solidly pro-precedent; the study actually put Thomas's views nearer the middle of the Justices', but again I don't quite see how one can sensibly do that, given the qualified nature of the Justices' stated views on the subject.)
There are lots of other possible problems here, some of which the article quite candidly delves into on PDF pages 33 and 34. But this problem alone should, I think, lead one to be quite skeptical of the New York Times assertions of a "wide gap" between the Justices' statements and their votes, and especially as to Justice Scalia. (I should say that the broader point that Justices' votes are hard to predict from their confirmation statements does strike me as correct.)