If we take a single sampling of a submitted product and run it on our instrument multiple times, each run is within ~1% (relative) of every other run of that same sampling (for most cannabinoids and terpenoids, for example). Thus, we might see values like the following: 15.5%, 15.3%, 15.4%, 15.7%, etc. These results have an absolute standard deviation of 0.17% or a relative standard deviation of 0.17%/15.5% = ~0.01 or ~1% relative. This gives a measure of the precision of the instrumentation method. Thus, the instrumentation gives very precise values of the sample of the product that was selected for testing. However, one measurement does not give any information about how another sample from that same batch might turn out, because each sample is a little different, even two samples from the same exact bud.
If we take multiple samplings from a submitted flower sample and run each sampling separately, then we might see, for the results from different samplings, something like 15.4, 13.7, 17.1, 16.5. This increased variation is due to the fact that flowers - even if it is just one bud - have significant heterogeneity, as is true of all biological entities. This variation is inherent in the sample and the only way to get around it is to make multiple tests of the batch and use the variability between the multiple samplings and tests to assess the variability within the batch. For some applications, it may be useful to get three tests (the minimum needed to adequately estimate the variation in the batch) and report a range that is representative of the variation in the batch. For this example, the average of the four sampling measurements is 15.7, but that doesn't give any indication of the variability. If, instead, one reported the "Range" (lowest to highest result) = 13.7-17.1, it may be more informative regarding the nature of the batch and would increase the likelihood that subsequent tests from that same batch (maybe submitted by your customer, etc.) will come in within or close to that range. This can eliminate disagreements like: "You said this was 16.5% but I had it tested and it came out at 15.4% and I want my money back."
Another possibility is to report the standard deviation. (Standard deviation is calculated by taking the root-mean-square of the differences between each measurement and the mean or the measurements.) S.D. = 1.5% for the four samplings reported above:
Avg. = 15.7%, S.D. = 1.5%
or a range based on the average and S.D.:
14.2% - 17.2%
or report relative standard deviation (RSD)
Avg. = 15.7%, RSD = 1.5%/15.7% = 0.1 or 10% relative
These methods convey considerably more information about the batch than a single measurement can. Please contact one of our scientific consultants for more information on your specific application.