POZ Community Forums
Main Forums => Living With HIV => Topic started by: newt on July 15, 2006, 01:32:47 am

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... 
50  1.7 
100  2 
330  2.5 
500  2.7 
800  2.9 
1,000  3 
3,300  3.5 
5,000  3.7 
8,000  3.9 
33,000  4.5 
50,000  4.7 
80,000  4.9 
500,000  5.7 
800,000  5.9 
1 million  6 
 matt "Viral load less than log 1.7" the newt