What's in a log? Reading viral load numbers and log values...

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newt:
Because I was asked, and there was a Q in another thread...

What's in a log?

Viral load can be expressed as a NUMBER or a LOG VALUE. A log is the number of times ten must be multiplied with itself to equal a certain number. For example, log 2 = 100 (10 x 10), log 5 is 100,000 (10 x 10 x 10 x 10 x 10).

Dividing a number by 10 is the same as a 1 log drop.

When comparing big numbers, it's sometimes easier to use logs because what looks like a massive change is in fact relatively small. For example: A viral load of 800,000 is log 5.9, 80,000 is log 4.9. So you's thinking "Wow! a massive drop in virus!" But in log terms it's the same as a drop from 500 (log 2.7) to 50 (log 1.7), which in number terms don't seems as grand as losing 720,000 of the little buggers does it...

A change in viral load of 0.5 log is significant.

You can convert a number into a log value by entering "log(THE NUMBER)" into the Google search box, for example enter "log(50)" and press RETURN and you will give you the result "log(50) = 1.69897".

HANDY LOG TABLE Viral load is...Log value...501.710023302.55002.78002.91,00033,3003.55,0003.78,0003.933,0004.550,0004.780,0004.9500,0005.7800,0005.91 million6 - matt "Viral load less than log 1.7" the newt