banner of Methodology for Determining Motorcycle Operator Crash Risk and Alcohol Impairment

3. Detailed Report of Discussion

Geo-Specific Comparison Data

Geo-Specific Comparison Data are comparison data collected at the sites of crashes in archival datasets. Most likely, crashes would come from the FARS dataset. Field researchers would go to the site of the original crash and stop one or more passing motorcyclists to collect population-at-risk data. Ideally data would be collected at the same time of year, day of the week and time of day as the original crash. If possible, multiple riders would be surveyed at each site. If it is not possible to find riders, or to survey riders at the exact location of the original crash, it may be necessary to obtain riders at a higher-traffic location somewhere near the original site. To do so would reduce the validity of results to some extent. In many ways, this method for collecting comparison data would be similar to the collecting of comparison data within the Contemporary Case Control study. Overall, this study would be very similar to the Geo-General Comparison data study.


This study has many of the same advantages as the Geo-General Comparison Data and Contemporary Case Control studies. The primary advantage of this methodology over the Geo-General study is that comparison data obtained at the location of the original crash may be a more valid comparison than data collected in different neighborhoods, cities or States, as may be the case with the Geo-General approach. The primary advantage over the Contemporary Case Control study is that it takes advantage of archival crash data.


The disadvantages of this study are also similar to those of the Contemporary Case Control and Geo-General Comparison Data studies. OMB clearance will be needed to survey riders, and the cooperation of riders, and possibly local law enforcement, will be necessary. The main disadvantages of this study over the Geo-General are that it may be difficult to find riders at the sites of the original crashes, and there will almost certainly be fewer riders surveyed. The main disadvantages compared to the Contemporary Case Control will be the greater time elapsed between case and comparison data and the fact that archival case data will not be as complete nor as accurate as the data collected by a go-team at the crash scene.


The costs associated with this study will be almost entirely in collecting the comparison data. Using archival crash data would result in great savings over the Contemporary Case Control study. However, the cost of obtaining the comparison data would be significantly high; therefore, this methodology has been placed into the high-cost category. It is not certain, but it seems likely, that the Geo-Specific method for collecting comparison data would be more expensive than the Geo-General method, given the labor involved in collecting data for each case, the large number of cases that would be needed, and the high likelihood that finding a motorcycle at some sites would require a long wait, and in some cases no motorcycles would be found.