It’s important to check your work. It helps prevent you from publishing stupid mistakes. It’s also important to check other people’s work. That helps prevent you from believing people’s stupid mistakes. Sadly, in the internet age of near-instantaneous communication, people often do neither.
Andy Skuce of Skeptical Science, who I follow on Twitter, recently retweeted this:
I like to keep abreast of who uses deceptive charts, so I clicked on the link to the Hot Whopper piece. I then scrolled down to the section, “How has Bob Tisdale fudged his chart?” In doing so, I saw the chart which was supposedly fudged:
I didn’t see anything out of place at first, but I read on. Sou (the site’s owner) claimed to plot the same data as Bob Tisdale and said:
Hmm. The chart I plotted from KNMI data is quite different to the one that Bob Tisdale constructed.
The side by side comparison Sou provided seemed especially damning:
I decided to check for myself. I went to the same site and got the same data the two of them had supposedly plotted. Here’s a screen shot of my result:
This is exactly what Bob Tisdale showed. This reinforced the suspicions I got when I saw Sou first present results:
That image, like the image from Bob Tisdale, has something not present in the side-by-side comparison: information about what data was used. Sou’s graph says “24S to 24N and 80W to 120E.” Tisdale’s graph says “24S-24N, 120E-80W.” Notice the subtle difference. The order for the second range is inverted.
To confirm my suspicions, I went back to the KNMI site and swapped my longitude values from 120 and -80 to -80 and 120. It gave me this graph:
Which shows the same data Sou showed. That proves the difference between their results is simply the choice of longitude range. One person used the longitude range to get data for the Pacific Ocean. The other person used the longitude range to get data for everything but the Pacific Ocean.
In other words, one person made an incredibly boneheaded mistake, failed to catch it (if and) when they checked their work, and apparently at least some readers didn’t catch it when they saw the graphs.
Since this topic is about checking work, I’ll leave it to readers to check and see which person made the boneheaded mistake. Was it Sou, or was it Bob Tisdale?