How to preserve points near zero when taking logs?

Question

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How should I transform non-negative data including zeros?

I have a question:

Suppose we have a data point $(0,10)$. We then convert to a log scale. Excel gets rid of this data point since the minimum x-value is $1$. How do we keep this data point?

Edit. Can't you change the x-coordinate to $1$? So instead we have $(1,10)$ instead of $(0,10)$. The rest of the values are not changed.

You can't take the log of 0, so you can't keep that data point if you want to take logs. — Peter Flom, Oct 11 '12 at 13:12
This Q will also be helpful for you: [How small a quantity should be added to x to avoid taking the log of zero](http://stats.stackexchange.com/questions/30728/). — gung - Reinstate Monica, Oct 11 '12 at 13:20

score 4 · Answer 1 · answered Oct 11 '12 at 13:12

4

The convention is to add a small constant to all values in a vector before taking the log, whether it's base-10 or base-e. So you might use, e.g., log(x+1) or log(x+.001), depending on which would have the least effect given the range of values you're dealing with.

answered Oct 11 '12 at 13:12

rolando2

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@ronaldo2: Can't you just change the x-coordinate to 1? – Rhubarb Joker Oct 11 '12 at 13:35

How to preserve points near zero when taking logs?

1 Answers1