The exact science of decaboxylliztion is more of an art. I've never read a study done with a mass spectrometer to determine the optimum time or temperature. I've found it's less about following an exact time and temperature for all types of bud, trim or extracted oil/kief - than starting somewhere in the middle (where your resin won't be vaporized but it's still hot enough to decarboxylize) and adjusting from experience.

223F for 15 minutes for dry trim does a great job for me, as does stuffing my toaster oven full of fresh cut leaves and baking for an hour at 225F. I cook my brownies at 300F to 350F, with an oven thermometer to guarantee temperature. The higher the temperature the less time you want to bake to avoid damaging the THC. Its always better to under heat than over heat.

The 1 - 3 hours in the crock pot is for extraction mostly, the decarboxylization is a serendipitous side effect but again with the process you will need a thermometer to check the temp and I never let it get any higher than 260F - 275F.

If there are any more opinions please add them..... The more information on this subject the better. Medibles are selling like crazy right now and those of us who do cook appreciate sharing info ; )