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Understanding Viral Load Assays for Cytomegalovirus and Epstein-Barr Virus


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Advantages of Logarithmic (log) Numbers

Slide 21

March 2010

The advantages of log do not stop at the better approximation of biological and laboratory phenomena. The transformation of integer values to log means that the results within a population are more closely approximate to a normal, or bell-curved, distribution. This is the first assumption necessary when using traditional statistics, and sound statistics are vital in providing evidence-based criteria for run acceptance in the laboratory.

Log numbers should also allow physicians to more easily trend patient viral loads. For example, if a patient viral load changed from 2000 to 4000 copies/mL (or 3.3 log to 3.6 log), the precision data from the literature and from our laboratory tells us that these numbers are statistically equivalent. Although the viral load has doubled, the reality is that because of biological and laboratory variation, there has been no significant change in viral load. On the log scale, the change was only 0.3 log, which is much less alarming.

Now let's take a moment to review integer and log numbers.

Advantages of Logarithmic Numbers


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