Construct and read logarithmic vertical axes, recover exponential models, and compare baseline assumptions using original-scale errors and unused predictions.
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What happens to a logarithm when its positive input is multiplied by ten?
Logarithmic axes represent ratios rather than equal additive differences.
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The base-ten logarithm increases by one: log₁₀(10u)=1+log₁₀u for u>0. Equal distances on a base-ten logarithmic axis therefore represent equal factors, not equal additions.
Which quantity changes proportionally in a shifted exponential?
A baseline changes what belongs on a logarithmic axis.
Compare reasoning and find a refresher
In y=k+A b^x, the excess y−k is proportional across equal x steps. Taking log(y) generally does not remove the additive k. Subtracting a proposed baseline is a modeling decision that still needs evidence.