tsillik said...
Isn't .05 less than .1
Yes.
It's always a good idea to write decimal numbers less than one with a zero in front of the decimal point. This avoids the confusion that always exists when you see something like .05.
Since the rule is to use the zero, the reader can't tell tell if the writer meant 0.05 (and left off this zero) or misplaced the decimal point (and actually meant 0.5). The zero serves to prevent confusion about
where the decimal point is, and not to be fussy.
You will never see a decimal lab result below one written without this zero, and grade school kids are taught to write decimals below one with this zero. (I do see advertising with numbers like
.1, but it looks terrible IMO. One reason is, perhaps, to make a number like .1%
seem larger than 0.1% when, for example, it's the percent active ingredient on a product package).
There is a big difference between a PSA result of, say, <0.1 and <0.01. The former was measured with the "standard" PSA test and the latter with an ultrasensitive test. (Thus the confusion if you write <
.1) Your PSA was "undetectable" with either result, but
<0.01 gives you more information. With a result of <0.1, you have no way of knowing whether your actual value is higher or lower than 0.01. However, if your result is <0.01, your actual value can only be lower (assuming for discussion these tests are 100% accurate, which of course they are not).
If you
change tests and go from <0.1 to <0.01, you gain information; going from <0.01 to <0.1 you lose information.
However, in both cases you don't know whether your PSA went up, down, or remained the same.Djin