Comparing two decibel values For my son's science fair project, we are measuring wi-fi signal strength in decibels, a logarithmic scale. We want to determine the relative strength of two values. I think that a value of -60 is 10 times weaker than -50. We want to graph the values taken at different distances. We can do so in decibels easily. But to really see the difference in signal, shouldn't we use a standard scale? How do we convert our list of values in decibel scale to a standard scale? Any other helpful comments on this approach would be appreciated.

The reason that we use logarithmic scales is because linear scales fail to provide good visual comparison of the data, typically resulting from the exponential behavior of the phenomenon we're observing.

The downside is that unless you are clever enough to understand that you're looking at a logarithmic scale, it's possible to obscure the magnitude of the phenomenon at hand. This may be the case for your target audience.

In such a case, I would recommend display the data in two scales -- linear and logarithmic -- and include a short discussion of what it means. If you can generate one plot, it is not hard to generate the other.

In truth, being able to comprehend the importance of scale is a non-trivial learning experience, for both your son and his audience.