The problem with surveys

December 7, 2013


I recently took a survey and as for many surveys, there were a few questions for which none of the answer choices seemed to fit. In the case of this survey, I knew the author of the survey and emailed him my concern. His answer illuminated things.

The survey was about prostate cancer treatment by proton beam therapy (a form of radiation) and the question was: “How would you describe the quality of your life TODAY: better than, same as, or worse than before proton treatment?” The author was thinking that proton beam therapy side effects are minimal as compared to – for some – the life altering side effects of surgery. Moreover, the author had non prostate related health counseling that improved his life so for him, the choice was clear – his quality of life was better.

For most of us, prostate cancer has no symptoms – the only way we know we have it is an elevated PSA followed by a biopsy. Also for most of us, proton beam therapy side effects are minimal but there are still side effects; hence the only logical way to answer the question is that quality of life is worse than before proton treatment. Of course, the quality of life for some might be better – say if you hit the lottery, but this is unrelated to treatment.

One way of preventing these issues is to test the survey with a subset of the intended recipients. This should help but perhaps another thing to do is to add a response to every question that is something like: “this question cannot be answered with the above choices.”

You don’t always get what you want – while flying

December 7, 2013


I wanted to fly from Norwood MA to Montauk, NY, which as a direct flight is 75 nm, as shown below.


I decided to fly IFR but the likelihood of getting a direct routing for a trip of this length is tiny. So I looked up previous routes and found and filed for this one, which is only 77 nm.


But when I called ground for my clearance, I was given this routing.


Not only is it longer (132 nm) including flying past my destination for about 20 nm (adds 40 nm to the trip), much more is over water. So I cancelled IFR and flew VFR.

To appear

December 7, 2013


An article has been accepted in the Journal of Diabetes Science and Technology for March which once again will critique the Westgard model of total error. In this case my critique focuses on glucose meters where Boyd and Bruns (1) model glucose meter total error and claim that if one sets goals for (average) bias and imprecision, one knows the total error of glucose meters.

My critique will show (by simulation) that if one has two glucose meters, where one is subject to hematocrit interference and the other not (yes, this happens) that the Boyd and Bruns model fails to distinguish any performance difference between these two meters but a correct way of measuring total error shows that the two meters have much different performance.

One could ask, why write this when I have already critiqued the Boyd and Bruns model and they responded that my critique was correct. The reason is that Boyd and Bruns have written subsequent papers using their model as if my critique never happened. And there is currently much emphasis on understanding how glucose meters perform.

  1. Boyd JC and Bruns DE Quality Specifications for Glucose Meters: Assessment by Simulation Modeling of Errors in Insulin Dose Clinical Chemistry 2001; 47:209-214.