Joel B. Greenhouse, Ph.D., is Professor of Statistics at Carnegie Mellon University, and Adjunct Professor of Psychiatry and Epidemiology at the University of Pittsburgh. He is an elected Fellow of the American Statistical Association, the American Association for the Advancement of Science, and an elected Member of the International Statistical Institute.
Professor Greenhouse is a recipient of Carnegie Mellon University's Robert E. Doherty Award for Sustained Contributions to Excellence in Education, the Ryan Teaching Award for Meritorious Teaching, and the College of Humanities and Social Sciences' E. Dunlop Smith Award for distinguished teaching and educational service. He was Associate Dean for Academic Affairs in CMUs College of Humanities and Social Sciences (1997-2002) and Vice-Chair of CMUs Faculty Senate (2015-2016).
Episode Description
What comes to mind at the start of summer? Backyard barbecues, quality time spent, and long drive. Transportation safety is the topic of this episode of Stats+Stories with guest Joel Greenhouse.
+Timestamps
What does this data system do? (1:10)
What did you know going into this? (5:00)
Does this change how drive? (6:10)
+Full Transcript
John Bailer: What comes to mind with the start of summer? Backyard barbeques? Family Gatherings? Quality time spent on long drives? Transportation safety is the focus of this episode of Stats and Short Stories, where we explore the statistics behind the stories and the stories behind the statistics. I’m John Bailer. Stats and Stories is a production of Miami University’s Departments of Statistics and Media, Journalism and Film and the American Statistical Association. Joining me online today are regular panelists Rosemary Pennington and Richard Campbell, both from the Department of Media, Journalism and Film. Our guest today is Joel Greenhouse. Greenhouse is Professor in the Department of Statistics at Carnegie-Mellon University. Last year Greenhouse cochaired a report on the Federal Voter Safety Administration’s Safety Measurement System. Boy, that’s a mouthful Joel. The program is used to identify commercial motor vehicle carriers at high risk for future crashes. Joel, thanks so much for being here.
Joel Greenhouse: Thanks for having me. Thanks, John.
Bailer: So, Joel you know, I doubt that many of us have even thought about the existence of such a data system. Can you tell us a little bit about what this data system does and why it exists?
Greenhouse: So, many federal agencies actually have statistics groups- which I wasn’t necessarily really aware of, but in the Department of Transportation there are several different statistics research groups, known as Bureau of Transportation Statistics. And then there is also another group that is responsible for monitoring the safety of long-distance drivers. So, long distance is not only trucks but also includes buses that go across state lines. And this group is mandated by Congress to monitor the safety and to report and regulate the different truck companies and transportation companies. And so the way I got involved in this through the National Academy of Sciences was that several years ago there was a transportation bill, which actually in the bill said that there should be a study done by the National Academy of looking at the scientific merits of the system that this agency was using to monitor the safety of long distance drivers. And this was a, as you might imagine, somewhat a controversial system that’s being used. Everyone was worried that they were not getting a fair shake, but the source of data for this system really comes from something that we’re all familiar with when we drive on the highway and we see inspection stations and you kind of wonder what are they for. Well actually there’s an inspector that can pull over a truck or a bus and there are several different levels of inspections that they can do. So, they’ll check the brakes, they’ll check the lights, they’ll interview the driver. And all this gets recorded. All of this information is actually a recorded at the state level and then gets uploaded to this national registry. And this agency over the years has come up with a system for trying to base on this non-random sampling or these sources of information to try and evaluate not the truck itself, but the companies- the different truck companies in terms of what their relative safety is. And then if they decide for various reasons using their system that a company might be not safe the various interventions, they can take including the most severe which would be closing down the company.
Richard Campbell: So, are these inspection stations- are these what we know as weigh stations? Is that where this goes on? Where they weigh the truck?
Greenhouse: I believe so yes. They weigh the trucks and they can do an inspection. Also, there are inspectors on the highways that can pull a truck over either based on some suspicion; they could see a headlight is out, so then they pull them over or they could just decide to stop them.
Bailer: So, what was the big key takeaway from the work that you and your group did?
Greenhouse: The key takeaway was that the agency had the right approach; they had a lot of good instincts. There were formalisms that they could use from a statistical approach that would actually be much more transparent, much more systematic, and more useful for them, in terms of how they interact with the public and with different companies. So that was our basic recommendation. That there was an approach to formalizing what they were doing and to make it much more systematic. I didn’t know anything about transportation when I was put on this committee. That’s sort of one of the fun things about being on National Academy Panel, but what I recognized was the problem- the nature of the data that they were collecting was analogous in terms of what we collect for safety hospitals. So, you have an outcome of a patient and you want to evaluate how safe is this hospital? Or you know, what is the mortality rate in terms of surgeries? So, there’s this hierarchy of data that gets collected and some of that- and some ranking of hospitals gets made and that’s the same thing that they do in this context of trucking companies. And so, my contribution was recognizing that analogy and then getting people that were expert in this type of problem, which also rises in educational research as well. You have kids within classrooms, classrooms within schools, schools within districts. And so, there was actually a lot of expertise and an approach to dealing with this data it’s just the transfer of that knowledge really hadn’t occurred in the transportation world.
Bailer: So, does this change your willingness to drive on the highway as a consequence of knowing this?
Greenhouse: Yeah the first thing I asked as I was learning about this was well, what do you do on the highway? They said get the heck out of the blind spots of those trucks as fast as you can.
Bailer: Well, Joel I’m afraid that’s all the time we have for this episode of Stats and Short Stories. Thank you so much for being here.
Greenhouse: Oh, I’m sorry if that took too long.
Bailer: It didn’t take too long this was perfect. You gave us a quick and easy takeaway for us to now think about as we’re on the road. So, Stats and Stories is a partnership between Miami University’s Departments of Statistics and Media, Journalism and Film, and the American Statistical Association. You can follow us on Twitter, Apple Podcasts, or other places where you can find podcasts. If you’d like to share your thoughts on the program send your emails to statsandstories@miamioh.edu or check us out at statsandstories.net and be sure to listen for future editions of Stats and Stories, where we explore the statistics behind the stories and the stories behind the statistics.