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spiral8888 t1_izfurx3 wrote

Reply to comment by MrMitchWeaver in [OC] How to spot misleading charts? I would like to hear your opinion on the subject, also any tips design-wise? by dark_o3

  1. As someone commented. If you make the Y-axis such that the left one is 10% of the top and the right one 90%, you can make any change, big or small look exactly the same on the graph. In those cases the conveys zero information. You might as well give the values as numbers.

The only situations where it could make sense to suppress the zero are those where the absolute value of the plotted thing has no meaning, such as air temperature. So,.most likely you would never want to plot air temperatures starting from 0K. In most cases the absolute values have meaning, which is why the suppression of the zero just misleads the reader.

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MrMitchWeaver t1_izgn5wo wrote

I agree that it can be used to mislead but that isn't always the case.

Take disposable income. Straight from Fred. https://fred.stlouisfed.org/series/DSPIC96

If you click on "view last 5 years" your Y axis is going to start way above zero. It just makes sense. If you click on "view max" you will get Y axis closer to zero because the range of values justifies it.

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spiral8888 t1_izi4gl0 wrote

First, I have to say that there is something wrong with the data behind the graph. I can't believe the yearly disposable income could have 20%+ jumps in a month.

Second, yes the 5 year graph is misleading as it makes it look like the disposable income doubled in a month and then fell back to the old level.

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MrMitchWeaver t1_izim1f2 wrote

First, that's because of the stymulus payments. It's an anomaly. We're not here to talk about the data itself though.

Second, if you actually look at the y axis it's not even a little bit misleading. This is the default setting for all Fred graphs. If you're showing a value starts at 15.000.000.000 you are not going to start the Y axis at zero...

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spiral8888 t1_izivw2d wrote

Yes, you can look at the Y-axis. But if you think that just by having the Y-axis values available removes all misleading, then no suppression of zero is ever misleading. For instance, by your logic the OP's first graph is not misleading as the values are there.

Regarding the Fed graph, the thing that you named as anomaly is amplified when you suppress the zero. When you don't the effect of the stimulus is put more context of how much effect it actually had on people's disposable income.

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Skulltown_Jelly t1_izgdzp4 wrote

That's not the only situation. Trend lines are graphs that are used to show...well.. the trends, and the absolute quantities are not as important in many cases.

Stock prices from a certain year are a good example. It's not that it doesn't have meaning, the price of the stock is valuable information, it's just not as important as the trend and depending on the amounts it could make the trend hard to read

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spiral8888 t1_izi3wng wrote

Two things. First, the stock prices are a bit like temperature in a sense that the absolute value of the share price has very little meaning. The share price of $10/share doesn't really tell you anything. It only tells you something in relation to the past.

Second, the relative change of the share price does matter. So, 50% drop in price is a different thing than a 1% drop. If you suppress the zero, they look the same on the graph.

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MrMitchWeaver t1_izgoma0 wrote

In OP's chart the problem is more the scale than the start point, but it's always about context.

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