Simpson’s Paradox and the MLB
Well, it’s October, and the World Series is under way. Good time to talk baseball I’d say. So here’s a blast from my own past on the subject: Simpson’s Paradox and Major Leagues Baseball’s Hall of Fame.1 In 1994 I wrote an article with this title1 for the AMATYC Journal, the official journal of record at […]
Edward Tufte in San Francisco, 10 December 2013
Edward Tufte in San Francisco, 10 December 2013 Written by Reynolds RJ and Day SM on January 06 2014 We recently had the pleasure of attending a seminar by one of the world’s experts on the presentation of quantitative data and information. At turns witty, sardonic, or professorial, “ET” (as he is affectionately known by […]
Immortal time bias: A source of bias in estimating life expectancy and other measures
One of the most important aspects of good research is proper study design; no type or amount of statistical analysis can make up for a poorly designed study. In longitudinal research one of the most important aspects of study design is making sure that the temporal sequence of events is understood and recorded correctly. Errors […]
Losing sleep over denominators, Part III: Explaining the error and the bias in Plioplys 1998
As we saw in Part II of this three part series, there is something wrong with Figure 4 in Plioplys et al. 1998.1 As a matter of fact, there is something wrong with all of the figures in the study, though it is a bit more difficult in some cases to confirm this. If the reader […]
Losing sleep over denominators, Part II: The survival curves in Plioplys et al. 1998 cannot be right
We now turn our attention to 1998 study by Plioplys et al.,1 and in particular to one of the many figures in the study: Figure 4. We choose to focus on this figure because the number of individuals involved in the analyses is small enough to make it very easy to see that something is wrong. […]
Losing sleep over denominators, Part I: An introduction to the problem of Plioplys 1998
Full disclosure: We consult professionally in the context of personal-injury litigation. One of us (SMD) has served on more than one occasion as an expert witness opposite Dr Audrius Plioplys. On 19 June 2013, Dr Tom Frieden, Director of the Centers for Disease Control and Prevention (CDC), delivered the Keynote Address at the 46th Annual […]
Radiation and astronaut mortality, Part 3: Dose Estimation Tool
In Part 2, I detailed how I gathered individual measurements of equivalent radiation doses for locations in outer space. Here I relate how I converted those measurements into a useful tool to estimate equivalent radiation doses for astronauts on past or future missions. The first task in this phase of the project was to enter […]
Radiation and astronaut mortality, Part 2: Gathering the measurements
In order to estimate radiation doses in space, I had to make some basic assumptions. First, I assumed that radiation dose levels would vary by some measurable factors: altitude, orbital inclination, and the type of spacecraft. If this were true, then the dose received would depend on how much time was spent at any given […]
Radiation and astronaut mortality, Part 1: Conceptualizing the problem
As part of my doctoral dissertation for my PhD in Epidemiology from the University of Texas Health Science Center at Houston, I completed a three-phase project which asked whether the mortality rates for astronauts increase with the amount of ionizing radiation they have absorbed in space. Though a simple question to ask, answering it presented […]