

Data-driven fallacy - mycodebreaks
http://cutchai.wordpress.com/2013/10/04/data-driven-fallacy/

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greenyoda
Manipulating the scales on graphs is one of the oldest tricks in the book.
It's one of the many deceitful practices that Edward Tufte talks about in _The
Visual Display of Quantitative Information_. In fact, in the chapter on
"Graphical Integrity", he writes: "For many people the first word that comes
to mind when they think about statistical charts is 'lie'."

If I were interested in investing in Twitter stock, I wouldn't be nearly as
concerned with the growth of their user population as I'd be in the growth of
their bottom line (profits). Oh, sorry, there are no profits.[1] As they say,
"you can't make up losses on volume".

[1]
[https://en.wikipedia.org/wiki/Twitter#IPO](https://en.wikipedia.org/wiki/Twitter#IPO)

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auggierose
I know very little about economy, but "you can't make up losses on volume"
does not sound right. Let's say you have fixed costs F per year and you make a
profit of P per user. Then as soon as numUsers * P >= F, you made up your
losses on volume.

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Noughmad
These are not losses. Losses are, as in Twitter's case, when P is negative.

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sokoloff
GP is surmising the case where marginal profit per user is positive, even
though average profit per user is still negative.

IOW, calling it I, net income per user, would have made the argument more
clear.

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svachalek
If you really need to clip off the bottom of your bar graph for clarity,
jagged lines do a wonderful job of explaining that instantly. I don't see the
point of a bar graph that doesn't start at 0 or indicate an omitted range,
_except_ to deceive.

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forktheif
Really?

How about if you're trying to show in detail a small change in a large number?
If the scale started at zero, all bars would look equal.

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eru
Don't use a bar graph, then.

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computer
Notice also that they plotted exactly 6 bars.

Choosing the start point is also a way to magnify perceived growth-- perhaps
the growth was much stronger before that and is actually levelling off? Of
course, if they had drawn 8 bars I could have said the same, so I'm not
accusing them of anything; I'm simply pointing out the possibility.

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Kiro
What a pretentious title to something newspapers do all the time and everyone
learns about in school when talking about source criticism.

