VIENNA, Va. -- A new study contends that Federal Motor Carrier Safety Administration safety data under its Compliance, Safety, Accountability program does not accurately predict crashes.

The Alliance for Safe, Efficient and Competitive Truck Transportation commissioned the study on the correlation between individual carrier percentile rankings and crash frequency based on data obtained from the FMCSA data bank.

The study shows that, with respect to individual carriers, percentile rankings of carriers both above and below the arbitrary "monitoring thresholds" -- indicated with the alert symbol (a yellow triangle with an exclamation mark inside) -- are not valid predictors of crash frequency.

The study comes on the heels of the American Trucking Associations calling for the FMCSA to release its own study on the link between violations and crash risk used to develop its methodology for assigning carriers scores under CSA.

The ASECTT study, conducted by Dr. Inam Iyoob, director of engineering at Transplace, a logistics technology and transportation management services company, says the FMCSA safety measurement system percentile scores account for less than 1 percent of the variation in crash frequency for each of its Behavior Analysis and Safety Improvement Categories (BASICs).

Iyoob says the FMCSA data cannot be used to predict the crash performance of individual carriers, even though the FMCSA says its Safety Measurement System (SMS) scores are correlated to the average crash frequency of hundreds of carriers at each percentile integral.

"I can't see any useful purpose in averaging the crash data of hundreds of carriers in each of 100 different percentiles and then calculating a regression of the average values," Iyoob said.

"The purpose of regression analysis is to explain variation. Averaging hundreds of carriers at each percentile eliminates most of the variation in the data.

"It is not statistically accurate to say the SMS methodology and BASIC percentile scores are an accurate predictor of carrier safety predicated upon the crash data the agency uses to justify its conclusions."

The study notes that logically, unsafe driving and driver fatigue do impact crashes.

However, the way the SMS BASICs for Unsafe Driving and Fatigued Driving are captured, calculated and interpreted by the FMCSA does not show any correlation to crashes, according to the study.

Read Iyoob's report at https://docs.google.com/file/d/0B6aiirmQGAQSTnQ2Y1dFOHMtQXc/edit?pli=1.