A place to ask questions and add to probative and informative discussions associated with the various aspects of the field of fire investigation. -- FORUM RULES---BE CIVIL AND NO NAME CALLING, NO BELITTLING, NO BERATING, NO DENIGRATING others. Postings in violation of these rules can be removed or editted to remove the offending remarks at the discretion of the moderators and/or site administrator.
Re: Acceptable Level of Certainty
Posted by:
Jim Mazerat (IP Logged)
Date: February 08, 2007 05:15PM
You are not mis-reading 921, it does not use the word “Must”. It was a mis-use of words on my part. You are right again when you say that 921 allows for a determination to be made if the level of certainty reaches the level of probable. In there definition of this term they indicate to reach the level of probable you opinion only needs in your mine to reach the level of slightly more than 50% chance of being correct. I find nothing wrong with an investigator expressing a level of certainty or confidence in their findings. Do you know of any science where 100% certainty is obtainable. It is my perception that in scientific predictions, a hypothesis, the only certainty is nothing is certain to the level of 100%. I agree in placing a degree of probable accuracy for the opinion being correct, most scientist give a percentage. My only problem is that using our terminology, “probable” could mean a percentage as low as 50% or one as high as 99.9%. Maybe the answer would be to remove the precentage range.
I believe what is being done in this case, as with classifications, is we are attempting to have a one size fits all. Knowing what I know today, if I were and attorney, I would be asking you not if your level was possible or probable but to what percentage you believe in your opinion being correct. Remember, when on the witness stand much of the trier of fact acceptance of our opinion comes from perception. I would like to have an expert on the stand indicate the level of certainty he or she has in the opinion being correct is only slightly above 50%. My comment to the jury would be, after that answer, is all this experts needs to do is flip a coin to get a 50% level of certainty.
What it seems is being said is one only needs to test their hypothesis until they find one that rises above the 50%.