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MrMitchWeaver t1_iziwq8f wrote

Reply to comment by Stannic50 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

If the unit is the same but the magnitude is very different it does not make sense to use the same axis.

Take housing growth YoY, unemployment, loan delinquency, labor force participation rate, yield curve.

These are all expressed in percentage points but they have wildly different ranges and magnitudes. It would make no sense to use one single axis for two or more of those.

As I said in my first comment. If the series justify the double axis chart it makes sense to use it.

Creator needs to be honest and consumer needs to be vigilant. Same as it ever was.

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marsman t1_izj00gg wrote

>These are all expressed in percentage points but they have wildly different ranges and magnitudes. It would make no sense to use one single axis for two or more of those.

And importantly, there is the potential for trends to be highlighted by that sort of chart that wouldn't otherwise be visible, and that are accurately reflected in the data (so its not a manipulation).

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Stannic50 t1_izjhx9m wrote

I agree. That's what I meant by "change over time within A/B." If the purpose of a graph is to show whether dogs or cats are preferred, then there should be a single % of households containing [pet] axis so the magnitude of the values can be directly compared. Whereas if the purpose is to show the effect of the 2008 recession on pet ownership, it may be more appropriate to have two separate axes so the magnitude of the change in values can be compared.

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