Just for your notice. In Germany breath tests are only used for a fast investigation. You can only be judged if a blood test also gives a positive result. And of course, if people are slightly below the limit in the breath test, they do a blood test, too!

Regards,
Johannes

assuming the device is unbiased (something that can easily be fixed if it where so by calibartion) you don’t really need a more accurate method. All you need to to is average over several measurements. The mean of n measurements will again be normaly distributed, but with a variance of 1/n*sigma^2 if the original measurements had a variance of sigma^2. So by simply repeating the procedure you get a much lower margin of error.

– Olaf