[HN Gopher] Truncating Bar Graphs Persistently Misleads Viewers
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Truncating Bar Graphs Persistently Misleads Viewers
Author : sebg
Score : 100 points
Date : 2021-02-19 15:14 UTC (7 hours ago)
(HTM) web link (www.sciencedirect.com)
(TXT) w3m dump (www.sciencedirect.com)
| pessimizer wrote:
| As an effective technique, it should be in everyone's toolbox.
| boringg wrote:
| It's similar to the lack of context. For example budget costs
| without context so people freak out on total dollar spent instead
| of how it fits in the context of historical spend. I would argue
| that time series plots should be given for most large number
| items so people have contextual history instead of going straight
| to outrage.
|
| Not that there is an incentive for most media organizations to
| present information in a reasonable way, would lower traffic and
| engagement.
| clairity wrote:
| your solution of time series for context seems like a form of
| appeal to authority. because it was x last year, x+5% can't be
| bad! (appealing to the authority of the budget maker in this
| case)
|
| appropriate context would be a breakdown of what x consists of,
| not just what it was last time period, and how that changed
| over time. then viewers can decide for themselves what's
| reasonable as a whole budget based on its parts. appropriate
| visualizations can provide breakdowns like this without much
| added complication.
|
| but as you noted, letting readers think for themselves is not
| in the interests of the media, whose power lies in the control
| they can exert on what we think.
| kevincox wrote:
| This is also similar to providing massive numbers without any
| context. For example $x produces 2.3M tonnes more $waste than
| $y every year!!! Of course $y produces 8.2T tonnes a year so it
| isn't /that much/ of a delta.
|
| Also vaguely related to my pet peeve of using large
| denominators to make numbers large and confusing. This factory
| produces 63M items a year! How about 2 per second, I can
| visualize 2.
| leetcrew wrote:
| > Also vaguely related to my pet peeve of using large
| denominators to make numbers large and confusing. This
| factory produces 63M items a year! How about 2 per second, I
| can visualize 2.
|
| smaller denominators can also be misleading though. maybe
| this is just me, but I usually read the denominator as
| implying a time period over which the figure is stable. for
| example, before the pandemic, I drove about 40 miles/day. I
| really did drive 20 miles each way to work pretty much every
| day. another way of saying this is that I drove 1.6
| miles/hour every work day. true _on average_ but kinda
| misleading when I spent 23 hours out of the day not driving
| at all.
|
| it might not matter much to your example, but the factory
| probably didn't produce two items every second. there were
| probably shift changes, or maybe it stopped production for a
| few hours every night. depending on market conditions, it
| might have produced more on some days than others, and so
| forth.
| kevincox wrote:
| That is true. There are cases where the timeframe is
| important, but often it isn't. I definitely should have put
| "on average" in there. You can also be more clear and say
| "Produces 5 per second when running at full capacity,
| averaging 2 per second throughout the year" if that is
| appropriate for the info you are sharing.
| hinkley wrote:
| There's a vague prescription in Thinking Fast and Slow that
| an objective person attempting transparency should present
| both versions of the numbers.
|
| Example:
|
| .15% or half a million Americans died. What policy changes if
| any should we enact to try to compromise between lives lost
| and GDP, as lower GDP compromises (for instance) our
| influence in the international community.
|
| Versus:
|
| Side 1: it was less than one in 800 people. This is hysteria.
|
| Side 2: What do you mean hysteria, we lost HALF A MILLION
| PEOPLE and it could have been 3 million if we had done it
| your way.
|
| Side 1: 1 in 800 is not that many.
|
| Side 2: 1 in 800 is a lot, actually.
| blululu wrote:
| Ed Tufte pointed out that Japan's newspapers were far ahead of
| American media in terms of presenting a large number of
| meaningful visualizations. He also pointed out that the
| Communist Party of Japan was the leader amping Japanese media
| on presenting charts. Needless to say there are important
| cultural factors at play here.
| __s wrote:
| The number of pixels representing quantities in a graph should be
| proportional to each other as what they represent. This also
| addresses perspective bias in slanted 3d pi charts
|
| Curious what biases one might also find based on color intensity
| of bars & varying widths
|
| Not sure how to balance out this idea with log scales, which can
| be useful, but require a bit more care in visually digesting
| birdyrooster wrote:
| Funny, I just added y-min: 0 to a lot of my grafana graphs today
| for this exact reason. It's really good to give yourself
| sufficient context when creating dashboards or you miss the
| bigger, more important picture.
| blakesterz wrote:
| You can read a preprint of this article here:
|
| https://psyarxiv.com/7aq4h/
| throwawayfb69 wrote:
| I'm not super convinced by this study.
|
| The examples show Fox News-levels of graph manipulation, i.e.
| maximum manipulation.
|
| This is clearly done in an attempt to communicate a particular
| message. If you read the questions as "What message was the
| author trying to communicate?", which is reasonable, then the
| study could show that you were willing to repeat back the
| author's intended message.
|
| In this sense, you weren't fooled by the graph - you understood
| exactly the message it was intended to convey.
|
| A truncated graph is, in my opinion, completely appropriate for
| data where the relative differences or trends in data points is
| more relevant to the message than the absolute values - a
| temperature chart, say (where the absolute values are pretty
| much meaningless).
|
| If you took data of a clearly relative type rather than a
| clearly absolute type, would you be able to say that viewers
| were misled in the exact opposite direction? That would be
| interesting.
| gus_massa wrote:
| A cropped _line_ graph may be fine. In particular, in a
| temperature graph, where should we put the horizontal axis,
| at 0degC, 0degF or 0K?
|
| The problem are truncated _bar_ graph. Using a truncated
| _bar_ graph is never a good idea.
| 7402 wrote:
| This could be considered a subset of the more general problem of
| trying to figure out when two points on a graph are meaningfully
| different, as opposed to just visually different.
|
| In my early physics training the importance of putting error bars
| on data points was stressed, allowing for a visual comparison of
| the difference between two points in standard deviations.
| OliverJones wrote:
| Sure enough. Edward Tufte calls this stuff "chartjunk."
|
| His books are really good sources for learning to do this data-
| presentation well.
| smartmic wrote:
| This is neither new nor surprising. I recommend the little book
| "How to lie with statistics" by Darrell Huff, first published
| 1954. Chapter 5, called "The Gee-Whiz Graph" dives into the
| matter of truncated bar graphs (among others).
| hanche wrote:
| Absolutely! I am happy to note that the paper does in fact
| reference _How to lie with statistics_ in the introduction:
|
| > While discussions of misleading graphs are not new (e.g.,
| Huff, 1954), empirical research on their assumed consequences
| is scattered across fields.
|
| So on the surface, at least, this looks like just another paper
| belabouring the obvious.
| btilly wrote:
| Wonderful. We now have research to prove what has been well-known
| and obvious for many decades.
|
| After all this exact form of misleading graph was one of the
| topics in the famous book _How to Lie With Statistics_ written in
| 1954. And I don 't think that the observation was new then.
| snshn wrote:
| We have to use the technology: animate bars on the X/Y scale on
| the graph, speed of the animation should be tied to the current
| max value represented on the graph. This way, humans will
| naturally recognize the value the current bars represent.
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