One of the most popular shows in the early years of television was hosted by Art Linkletter, which included a segment called “Kids say the darndest things.” Linkletter would have conversations with young children who could be counted on to say things that adults found entertaining. I’ve experienced my own version of this in recent years that could be described as “Researchers say the darndest things.” My conversations with the authors of data visualization research studies have often featured shocking statements that would be amusing if they weren’t so potentially harmful.

The most recent example occurred in email correspondence with the lead author of a study titled “Evaluating the Impact of Binning 2D Scalar Fields.” I’m currently working on a newsletter article about binned versus continuous color scales in data visualization, so this paper interested me. After reading the paper, however, I had a few questions, so I contacted the author. One of my requests was, “I would like to see the full data set that you collected during the experiment.” Here’s the response that I received from the paper’s author: “In psychology, we do not share data sets but the full analyses are available in the supplementary materials.” You can imagine my shock and dismay. Researchers say the darndest things!

Withholding the data that was collected in a research study—the data on which the published findings and claims were based—subverts the essential nature and goals of science. Published research studies should be accompanied by the data sets on which their findings were based—always. The data should be made readily available to anyone who is interested, just as “supplemental materials” are often made available.

Only good can result from sharing our research data. If we share our data, our results can be confirmed. If we share our data, errors in our work can be identified and corrected. If we share our data, science can progress.

Empirical research is based on data. We make observations, usually in the form of measurements, which serve as the data sets on which our findings are based. Only by reviewing our data can the validity of empirical research be confirmed or denied by the research community. Only by sharing our data can questions about our findings be pursued by those who are interested. Refusing to share our data is the antithesis of science.

The author’s claim that, “In psychology, we do not share our data” is false. Psychology researchers do not have a “Do not share your data” policy. I’m astounded that the author thought that I’d buy this absurd claim. What is true, however, is that, even though there is no policy that research data should not be shared, it usually isn’t. On many occasions this is not an overt act of omission, but a mere act of laziness. The data files that researchers use are often messy and they don’t want the bother of structuring and labeling those files in a manner that would make them useful if shared. On more than one occasion I have requested data files only to be told that it would take too much time to put them into a form that could be shared. This response always makes me wonder if the messiness of those files might have caused the researchers themselves to make errors during their analysis of the data. When I told a respected psychology researcher friend of mine about the “In psychology, we don’t share our data” response that I received from the study’s author, he told me, “In my experience, extreme protectiveness about data tends to correlate with work that is not stellar in quality.” I suspect that this is true.

If you can’t make your research data available, either on some public medium (e.g., accessible as a download from a web page) or upon request, you’d better have a really good excuse. You could try the old standby “My dog ate it,” but it probably won’t work any better than it did when you were in elementary school. If your excuse is, “After doing my analysis and writing my paper, I somehow misplaced the data,” the powers that be (e.g., your university or the publication that made your study public) should respond by saying, “Do it over.”

If I could set the standards for research, I would require that the data be examined during the peer review process. It isn’t necessary that every reviewer examine the data, but at least one who is qualified to detect errors should. Among other potential problems, calculations performed on the data should be checked and it should be determined if statistics have been properly used. Checking the data should be fundamental to the peer review process. If this were done, some of the poor research that wastes our time each year with shoddy work and false claims would remain unpublished. I realize that this would complicate the process. Well, guess what, good research takes time and effort. Doing it well is hard work.

If you want to keep your data private, then do the world a favor and keep your research private as well. It isn’t valid research unless your findings are subject to review, and your findings cannot be fully reviewed without the data.

Take care,