Using a logarithmic scale to represent COVID-19 growth

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Discussion Overview

The discussion revolves around the use of logarithmic scales to represent COVID-19 growth data, exploring how different scales can affect the interpretation of the data. Participants share insights on the advantages of logarithmic versus linear scales, express interest in visualizing the data on a log-log scale, and discuss the implications of using such representations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose that logarithmic scales provide a clearer understanding of COVID-19 growth, as linear scales can obscure data from countries with lower case numbers.
  • Others agree that on a log scale, the total cases outside of China appear to be growing exponentially, maintaining a straight line, which suggests consistent exponential growth.
  • Several participants express interest in visualizing the data on a log-log scale, questioning how it might differ from log-linear representations.
  • One participant raises concerns about the use of a logarithmic date axis, noting that it lacks a well-defined zero and may not effectively represent the data.
  • Another participant mentions that while a log-log plot could revert the shape back to exponential, interpreting the time axis in logarithmic terms could be challenging.
  • A participant shares that they obtained data from the source code of a webpage, specifying that all logs are to base 10 and noting a specific point in time where growth began to increase significantly.

Areas of Agreement / Disagreement

Participants generally agree on the potential benefits of using logarithmic scales for data representation, but there is no consensus on the effectiveness or interpretability of log-log plots, and some express skepticism about the use of a logarithmic date axis.

Contextual Notes

Participants mention limitations regarding data access for re-plotting and the challenges associated with interpreting logarithmic scales, particularly concerning the time axis.

scottdave
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TL;DR
I came across this interesting thread showing the difference between linear and logarithmic scales when visualizing coronavirus infections.
The author, John Burn-Murdoch, shows here ( https://threadreaderapp.com/thread/1237748598051409921.html ) how the logarithmic scale can give a better "sense" of what is happening. In linear scales, some countries' data is squashed to almost nonexistent, while others explode out of control.

I wasn't sure where the best place to post this - I thought it was interesting and wanted to share.
 
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I agree that the log scale is more informative. This site has a lot of good information, and allows you to toggle back and forth between linear and log scales. Note that on a log scale the total cases outside of China has been growing exponentially since February, and shows no sign of departing from a straight line (exponential growth).
Cases.png
 
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phyzguy said:
I agree that the log scale is more informative. This site has a lot of good information, and allows you to toggle back and forth between linear and log scales. Note that on a log scale the total cases outside of China has been growing exponentially since February, and shows no sign of departing from a straight line (exponential growth).
View attachment 258928
I'd be interested in seeing what this looks like on a log-log scale plot. Any chance you would consider doing that?
 
Chestermiller said:
I'd be interested in seeing what this looks like on a log-log scale plot. Any chance you would consider doing that?
I don't actually have easy access to the data to re-plot it. Why are you interested in that? Exponential growth should be a straight line on a log-linear plot, and it looks like that is what we are seeing.
 
phyzguy said:
I don't actually have easy access to the data to re-plot it. Why are you interested in that? Exponential growth should be a straight line on a log-linear plot, and it looks like that is what we are seeing.
I don't know why. I just like to look at the data in different ways, and I though that it would even be straighter on a log-log plot.
 
A logarithmic date axis? It doesn't even have a well-defined zero to use.

It won't make anything look straight. It will compress the time where the cases explode even more.
 
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mfb said:
A logarithmic date axis? It doesn't even have a well-defined zero to use.

It won't make anything look straight. It will compress the time where the cases explode even more.
I’d still like to see what the log-log plot looks like.
 
Chestermiller said:
I’d still like to see what the log-log plot looks like.
By putting both axes on a log scale, the general shape should go back (from the log-plot) to the exponential shape. Both axes of the original plot will be distorted similarly. But I think that the log of the time axis will be hard to use or interpret.
 
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Chestermiller said:
I’d still like to see what the log-log plot looks like.
I got the numbers from the source code of the webpage.
coronaloglog.png

All logs to base 10. Note that the point where the growth starts to increase at 1.47 or so is at about 20 february
 
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  • #10
willem2 said:
I got the numbers from the source code of the webpage.
View attachment 258972
All logs to base 10. Note that the point where the growth starts to increase at 1.47 or so is at about 20 february
Thanks very much. I was most interested in the part between 1000 and 300000 cases.
 

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