Offhand, I can't think of a case where a conservative scholar or institution announced a finding and then refused to release the data on which it was supposedly based. But I know of a number of occasions where that happened on the Left.
Michael Bellesiles (pronounced Bell-Leel) published a book Arming America in 2000, in which he argued that gun ownership was far less common in antebellum America than historians had suspected. The point, of course, was the right to bear arms wasn't something that the founding generation and subsequent generations really cared about. Bellesiles' book received glowing reviews across the MSM, and he won the Bancroft Prize.
The book was a fraud. It was riddled with errors, and much of the data was apparently invented. When asked to produce it, he claimed that it has been damaged when an office flooded. For the first time, the Bancroft prize was withdrawn.
Much the same thing has recently happened in the global warming debate. The records of climate history on which the Anthropogenic Global Warming thesis is based rely on a small number of data sets. The researchers who maintain those data sets have consistently refused to release them to the scrutiny of skeptical scientists, in one case in defiance of court orders. In another case, it was claimed that the original data was lost.
Now we have a third such example. From the Chronicles of Higher Education:
Judge Curtis E.A. Karnow of the California Superior Court for San Francisco County ruled last week that the state bar is not legally obliged to release the data sought by Richard H. Sander, a professor of law at the University of California at Los Angeles, and Joe Hicks, a former governor of the California state bar who is involved in a consortium of affirmative-action researchers organized by Mr. Sander. The two men were joined by the California First Amendment Coalition in their lawsuit, which seeks state-bar data on law students broken down by race and ethnicity.
Here is the question. Affirmative Action is the practice of giving preference to minority candidates in hiring and university admissions. In almost every case, minority status is weighted so heavily that a student who can claim such status can secure admission to the most competitive schools even if his or her test scores and academic record would have automatically disqualified a non-minority applicant.
One of the reasons offered for Affirmative Action is that it will increase the number of lawyers, doctors, etc., who are African American, Hispanic, etc. But does it in fact do that? Students whose academic preparation is modest will often fail when they are placed in the most competitive schools, whereas they might have flourished in a more typical institution. Does Affirmative Action really increase the number of minority students graduating from law schools and entering the legal profession? Or does it rather decrease the number by setting up many promising students for failure in programs for which they are ill-prepared?
That is what Sanders and Hicks want to find out. But the California State Bar refuses to release the data. I think we can assume the answer. When people refuse to release data, it is always because they think the data will confirm something that they don't want to see confirmed. Affirmative Action isn't helping minority students, it is hurting them. But the Left loves the idea of Affirmative Action more than it cares about the real people affected by such policies.
Hiding the data has become a habit in modern times. That is a sign of corruption. No doubt conservatives would be tempted to do it too, if they could get away with it. With the establishment Press and academia arrayed against them, they can't. The California Bar Association, so far, can.