NEW YORK (CNNMoney.com) -- State laws that ban drivers from talking on hand-held cell phones seem to have no effect on crash rates, according to a study released Friday.
The Highway Loss Data Institute compared collisions of 100 insured vehicles per year in four different jurisdictions before and after bans on handheld cell phone use took effect. The study was done in New York, Washington, D.C., Connecticut and California.
Data were also collected from nearby states for comparison.
Monthly fluctuations in crash rates didn't change after bans were enacted, the study found. Crash rates compared to nearby places without handheld phone bans also didn't change.
Earlier studies by the Institute, which is funded by insurance companies, found four-fold increases in injury-related crash risk associated with cell phone use, so this result was surprising. Surveys of driver behavior following bans raised more eyebrows. They showed actual reduction in cell phone use, the Institute said.
"We're currently gathering data to figure out this mismatch," said Institute President Adrian Lund.
One possible reason, Lund suggested, is that drivers are simply switching to hands-free phone use. Still, some studies suggest that the risk of hands-free phone use while driving is little different from handheld phone use.
Institute spokesman Russ Rader suggested that laws attacking particular types of distraction may be ineffective because there are simply too many distractions available to drivers for laws dealing with just one to have much impact.
"Whatever the reason, the key finding is that crashes aren't going down where hand-held phone use has been banned," Lund points out. "This finding doesn't augur well for any safety payoff from all the new laws that ban phone use and texting while driving."
When Netflix went public in 2002, its business model was renting DVDs over the Internet. Now, it is a legit global media giant thanks to hits like "House of Cards" -- and its stock has outperformed Apple, Amazon, Facebook and Google. More
Carrier plant in Indianapolis that Trump helped save cutting 300 jobs right before Christmas. More
In 1998, Ntsiki Biyela won a scholarship to study wine making. Now she's about to launch her own brand. More
We talked to seasoned employers, who have clocked thousands of interviews between them, to hear what strategies set apart the superstars they hired from the merely proficient candidates they let walk out the door. More