log graph scale

[Bill Wright]

Why does it start at 1? How do I display a score of zero?

Bill

[Ash Burton]

Most log graph paper i've seen starts with a y value of 0 and an x value of 1.

Why would you want an x value of 0?

[Archibald Tarquin Blenkinsopp]

You have not heard of the big bang?

AB

[The Natural Philosopher]

You dont.

IIRC the log of zero is minus infinity

[The Other John]

Because 10^0 = 1?

[Chris Hogg]

You need a bigger piece of graph paper; MUCH bigger!

[Bill Wright]

Because some of the quantities are zero.

Bill

[Bill Wright]

So all I can do is put the quantities that are zero on the bottom line?

Bill

[Bill Wright]

What I'm doing is making a column graph of the numbers of referrals from about a hundred sources. Some of the sources have referred no work in the time period the graph covers. Some have referred in single digit quantities; some in two digits, and some in three. So my scale has to go from 0 to 1,000. The single digit responses and the zero responses are quite important because they are the ones where Sales are going to have to put some work in.

I would have liked to show the zero responses on the graph.

Bill

[Andrew]

On a UNIVAC-418-III, Octal 777777 was minus zero (it was ones complement machine :-) )

[Chris Hogg]

enter them as 0.1, or even 0.01? Then your scale becomes

0.1,1,10,100,1000, or 0.01,0.1,1,10,100,1000

[jkn]

Then make a histogram with 'bins' of referral figure ranges. These could be strictly logarithmic, or something a little simpler.

bin 0: 0 referrals bin 1: 1--10 referrals bin 2: 11--100 referrals bin 3: 101 -- 1000 referrals

etc. make the bins finer if you want.

J^n

[Johnny B Good]

More accurately, *any* value to the power of zero is one.

[John Rumm]

Why not plot number off referrals plus one... then its s simple task to adjust when reading the graph.

[newshound]

If you would explain exactly what your problem is, perhaps we can help. You can have log/linear graphs or log/log ones. No problem putting zero or negative numbers on a linear scale. As TNP points out, the log of zero is minus infinity, so you need an infinitely large piece of paper to put zero on it.

[Graham Nye]

This seems a handy suggestion. You'll get a clear distinction between the zero and one referral cases and the sources of hundreds of referrals you're not fussed about will be squashed together.

[Robin]

I agree with the suggestion of using less than 1 instead of 0. It makes them really stand out "below the line".

And, assuming you are using a spreadsheet, you could try plotting with log base 2 or base 4 rather than base 10 to vary the "squashing" so as to focus better on the low numbers you want pursued.

[dennis]

I don't see why a graph would be useful at all. A table sorted by referrals with the low values first would indicate where the work needs to be done or not. With a graph you don't know where it needs to be done just that it does need to be done. There is also the issue of should you waste effort trying to get zero referrals up rather than getting the lots of referrals up and the graph won't help at all.

[Ash Burton]

some of your x values are zero?

the log of zero is minus infinity.

[The Other John]

I know, but Bill didn't state the base of his logs, I therefore assumed it was 10.