When you are trying to determine if malolactic fermentation is complete, do you need to know if your malic acid level is 30.25 vs 30.30, or do you need to know if it is 30 vs 40?
When you want to see if your Free SO2 adjustment came out correct, do you need to know if the Free SO2 level is 50.2 vs 50.3, or do you need to know if it is 50 vs 60?
For most wine processing decisions, the information provided by the first pairs of numbers does not help you decide what to do. The second of each pair of numbers does. This has to do with how much precision is needed.
How about another question, what if one test result for a malic acid level was 30.25, and a second test result was 40, and the true value of malic acid in the wine was 41.1? The first result looks precise, but it is precisely wrong. The second result is less precise, but much more accurate. This has to do with the appropriate level of accuracy you need. Lab testing provides the answers in hundredths, but is too often wrong!
Don’t be confused with testing that provides lots of extra decimal points that are of no value in your winemaking decisions, and especially if those extra decimal points are unreliable.
More information can be found in the white paper, “The Great Hundredths Hoax”, found in the Library section of The Wine Lab on Accuvin’s website, at http://www.accuvin.com/wp-content/uploads/2016/03/The-Great-Hundredths-Hoax-rev.pdf