How to Spot a Misleading Graph

"You can’t have it both ways."

Exactly. This clip is more accurately titled "Example of a Misleading Video". It's OK to use a suppressed zero on a graph in order to propagandize climate change it's not OK when comparing domestic vs. foreign car companies.

The fact about the truck chart is that Chevrolet trucks needed half as many repairs as the Toyotas. That's an important point if you keep a truck for a long time (as most buyers do). The fact about the temperature chart is that the time scale of 1880 to 2016 was chosen to eliminate the "Little Ice Age" from which the temperatures are still recovering, and the "Medieval Warm Period" with temperatures higher than they are now.

Their rule seems to be: "Use suppressed zeros to prove something I agree with, and don't use suppressed zeros when I disagree with your conclusion".

The first example showed how an “evil capitalist enterprise” used a selective scale to highlight “minor” differences. The last example used the exact same technique to highlight tiny climate changes, which are somehow more valid. Doublespeak to the max.

I ran across one a week or so ago. It was a CNN graph showing the percentage increases in viewership over the previous rating period. I wish I had bookmarked that now.

It basically showed CNN growth at huge percentages over the previous rating period. However, it did NOT give any actual viewership numbers. Thus, if CNN had 100 viewers last month and 150 this month, they could claim a massive percentage increase (50%), while the actual increase is only 50 viewers.

It was deceptive in that it claimed CNN has the largest PERCENTAGE increase in viewers of any news network.

The example was a graph showing the reliability of Chevy trucks seemed to show that Chevy is twice as reliable as Toyota and several times more than Nissan—but the graph really shows that they are all better than 95% reliable, and there is only a ~3% difference in reliability between the most and least reliable. But then, at the end, the narrator explains that an ocean temperature graph showing little change since 1880 is misleading because it *didn’t* change the scale to exaggerate the change.

If you want to determine how graphing techniques can be manipulated, you have to apply the same standards across the board.

Yes and no. On face value, you are absolutely correct. But then, arguably, you would always express/plot temperature in degrees Kelvin or degrees Rankine. That is, referenced to absolute zero based on perfect gas theory. Which has bupkis to do with whether you can grow bananas.
So rather than saying that the scale of a graph imparts a “bias," it is the fact that any scale explicitly or implicitly expresses a perspective.
Just try to plot the price of a stock without biasing your estimate of the future price.

I have never heard of degrees Rankine before. And for most purposes, it makes no difference whether I plot temperature differences in degrees Celsius or Kelvin—the only change would be the magnitude of the number on the y axis.

I love to make graphs. When done correctly, they convey a lot of information. You have to be honest about the graphs, though—if you are graphing two similar data sets and using different scales, you need to point that out very clearly. Just as you need to state all of the assumptions used in creating the graph.

I’ve never graphed stock prices, only scientific stuff.

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