Biostats: Francesca Dominici & Matthew Cefalu

Date: 

Friday, April 11, 2014, 12:30pm to 2:00pm

Location: 

HSPH Building II, Room 426
Completing the Results of the 2013 Boston Marathon Flashback to the 2013 Boston Marathon. It was a beautiful day; the runners were nearing completion of an exhausting 26-mile run when suddenly two bombs detonated near the finish line, resulting in three deaths and several hundred injuries. Over 6,000 runners were unable to finish the race after this horrific incident. We were approached by the marathon's organizers, the Boston Athletic Association (BAA), and asked to recommend a procedure for projecting finish times for the runners who could not complete the race. With assistance from the BAA, we created a dataset consisting of all the runners in the 2013 race who reached the halfway point, but failed to finish, as well as all runners from the 2010 and 2011 Boston marathons. The data consisted of split times from each of the 5 km sections of the course, as well as the final 2.2 km (from 40 km to the finish). We will present several statistical approaches to predict the missing split times for the runners who failed to finish in 2013. We created a validation dataset to measure their performance by mean squared error and other measures. The best method used local regression based on a K-nearest-neighbors algorithm (KNN method), though several other methods produced results of similar quality. We will show how the results were used to create projected times for the 2013 runners and discuss the potential for future applications of the same methodology. We will present the whole project as an example of reproducible research, in that we are able to make the full data and all the algorithms we have used publicly available, which may facilitate future research extending the methods or proposing completely different approaches. Paper to appear in PLOS ONE on April 11 2014 at noon. Embargoed until 5 pm. Hammerling D, Cefalu M, Cisewski J, Dominici F, Parmigiani G, Paulson C, Smith R, Completing the Results of the 2013 Boston Marathon, PLOS ONE.