Thread by @ikashnitsky, if I had just one shot to share an important ideahere it [...]

Ilya Kashnitsky

ikashnitsky

Read on Twitter

if I had just one shot to share an important idea

here it is. No joke. Look

RATIOS DEMAND LOG SCALE

the coolest non-trivial example when a log Y-axis is required to represent ratios

going from 50 in ~1988 to 25 in ~2001 is as bad as going from 100 in 1970 to 50 in ~1988

if I had just one shot to share an important ideahere it is. No joke. Look RATIOS DEMAND LOG SCALE the coolest non-trivial example when a log Y-axis is required to represent ratiosgoing from 50 in ~1988 to 25 in ~2001 is as bad as going from 100 in 1970 to 50 in ~1988

Fascinating how the data story is changing – the seeming recent plateau is no longer there. And log *is* the *right* way to represent the nature of the data and tell the story.

The plots above are made by @CedScherer using @WWF data via @OurWorldInData https://ourworldindata.org/grapher/global-living-planet-index?country=~Freshwater

Living Planet Index

The Global Living Planet Index (LPI) measures the average decline in monitored wildlife populations. The index value is measured relative to 20,811 populations of 4,392 species in 1970 (i.e. 1970 =...

https://ourworldindata.org/grapher/global-living-planet-index?country=~Freshwater

Here are the two tweets by @CedScherer prepared for today's #30DayChartChallenge https://twitter.com/CedScherer/status/1380223704811106308

https://twitter.com/CedScherer/status/1380223704811106308

RATIOS appear whenever you divide something by something else of a similar class/nature. Ratios are dimensionless. The most common "hidden" case is time series standardisation when some year is taken for 100%, like 1970 in the example above

The thing is: the story (the shape of the line) will change depending on the arbitrary choice of the year taken as 100%. We divide all other years by this standard effectively creating *ratios*

I genuinely believe this is *the* most common #dataviz issue

It also often becomes a problem in statistical analysis – log transformation of the ratios are required before regression/correlation analysis is performed on the data

[side note]
It's even more important than the ones coming right after:
– #RotateTheDamnPlot
– #IncreaseTheDamnFont

The realisation of this simple data visualization and analysis rule literally took me ages of slow mind walk: from odds ratios through other explicit ratios to the "hidden" ones like here. Even color bars in the plot legends should be log transformed if they colorcode ratios!

I lost track how many times I've pointed this out

RATIOS DEMAND LOG SCALE

The idea to write a blog post on visualizing ratios correctly lives in my head and to-do list for well over a year now

Let me use this thread to legally bind myself to write it up soon

You can follow @ikashnitsky.

Tip: mention @twtextapp on a Twitter thread with the keyword “unroll” to get a link to it.

Latest Threads Unrolled: