What is a $\log_{10} \%$ transfer? I have this graph of results comparing the transfer percentages of bacteria to hands with and without gloves. By the looks of things, the higher the bacteria count on the chicken the lower the transfer $\%$. But what's a -ve $\log_{10} \%$ transfer? Is that $(1-10^{-4})100=99.99 \%$? Makes no sense, how could you possibly transfer nearly ALL the (eg $\log 100,000,000 = 8$) bacteria on one surface to your hands? Or am I missing something here?

 A: This looks biology. Let's take a look at the horizontal axis. Let the number of CFU on the chicken be $x_{CFU}$. The value on the horizontal axis, moving outwards is on increasing $
\log$ of $x_{CFU}$. If $$\log x_{CFU}=7.5$$, then we can see $$x_{CFU} = 10^{7.5}$$. It is an easier way of representing it on a graph.
Similarly, let the percentage transfer be $y_{CFU}$. I'll leave you to do the calculations similar to the above. Let's take this answer one step further with some analysis. If $$\log y_{CFU}=0$$, then $$y_{CFU}=10^0=1\%$$
It seems that for full transfer with bare hands, the number of CFU is around $10^{8.0}$ and $10^{8.5}$. There seems to be an optimum number here.
Also, at the same range on the $x$-axis, wearing gloves reduces the percentage of transfer from above $1\%$ to anywhere between $0.01\%$ and $0.0001\%$. What you can see here is that because those numbers decrease so drastically in orders of $10$, using a logarithmic scale on both axes helps in the readibility of the graph.
