
I hate stacked area charts (2011) - dmitrig01
http://www.leancrew.com/all-this/2011/11/i-hate-stacked-area-charts/
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nostromo
I agree with the problem but disagree with the solution. I'd much prefer
removing the stack completely and using overlapping plots, like this:

[http://i.imgur.com/zO7CuQG.png](http://i.imgur.com/zO7CuQG.png)

In a chart like this no data is lost in presentation. You can easily answer
questions like "when did Android overtake iOS in marketshare?" and "is Windows
Phone marketshare growing or shrinking?"

~~~
TazeTSchnitzel
I don't like percentage plots. If one thing goes up by 1 point, then the rest
must necessarily go down by 1 point (distributed between them). I think that's
a bit confusing. I'd much prefer absolute values.

~~~
Kiro
Isn't that exactly how it's supposed to work?

~~~
ZeroGravitas
Yes, but human being seem to struggle with the concept, regularly assuming
that a decreasing percentage necessarily implies a decreasing absolute number
as well.

If they aim is to communicate a true representation of reality then you need
to take that into account.

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LeoPanthera
I was going to leave this as a comment on his blog but apparently comments are
closed now.

Stacked bar charts are better, but only a little better.

Line charts overlaid on top of each other are most clear, to me.

Like this: [http://i.imgur.com/kyvpiax.png](http://i.imgur.com/kyvpiax.png)

~~~
DigitalJack
To me they are far and away the worst, probably because I'm color deficient.

~~~
frik
Can you recommend an Excel addon/color chooser or website so that persons with
normal vision can test their charts and color choices for the four known kinds
of color deficients?

It would of cource help you, if the chart lines have different line patterns
(dottet lines).

~~~
widdma
[http://colorbrewer2.org](http://colorbrewer2.org) has some good palettes for
data presentation which they describe as "colorblind safe". I assume this
means for all kinds of deficiency.

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badusername
While I agree to some of the points made in the post, I don't think the author
provided a better alternative. Stacked bars are not any better for looking at
how the percentage change on the green one.

[http://i.imgur.com/jfuJGu5.gif](http://i.imgur.com/jfuJGu5.gif)

Here is my solution:

* It retains the line aspect of it, which is essential as we are talking about a trend here.

* It easily allows you to see it both in stacked and overlapped lines. Each one of them is good at communicating clearly a certain point about the data.

* It also mitigates the problem in nostromo's comment, where a whole bunch of lines could overlap without a clear view on a single point of interest.

~~~
dredmorbius
That doesn't translate to print (a problem with any dynamic content). Or even,
say, to static screenshots.

~~~
badusername
Who's still printing these days? :) It's safe to say that iPads and
smartphones have made it easy to consume content anywhere needed. Interactive
documents are definitely where the puck is headed.

~~~
dredmorbius
It happens more often than you'd think, and as I noted, even static
screenshots or images won't reflect the dynamic nature of that graphic.

Those are both issues you could address with small multiples, a Tufte method.

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arnarbi
The stacked bar chart is no better. Yes, it doesn't have the same distortion
of making green look smaller towards the right, but it is very hard to see the
slow growth.

Just use a normal line chart.

~~~
rschuetzler
It's not perfect, but it's definitely better.

~~~
nanoanderson
Yes, it's better, but using "better" stacked bar charts is not the advice I
want people taking away from an otherwise valid complaint about stacked area
charts. Volume is a [colorful] distraction.

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cscheid
Here's a recent paper about how to compensate for this very illusion, by Heike
Hoffman and Marie Vendettuoli:
[http://users.soe.ucsc.edu/~pang/visweek/2013/infovis/papers/...](http://users.soe.ucsc.edu/~pang/visweek/2013/infovis/papers/hofmann.pdf)

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russelluresti
Rabble rabble rabble.

The solution described is incorrect. Area charts and column charts are used to
display different types of information. Area charts (and line charts,
similarly) are used to display continuous data - data that must pass through
point B to get from point A to point C. Column charts are used for non-
continuous data.

Some examples:

You should use an area chart (or just a line chart) when tracking your weight.
If you weigh yourself on Tuesday and you weigh 150 lbs, and then weigh
yourself on Thursday and you weigh 155 lbs, because of how weight works, you
can assume that between Tuesday and Thursday your weight traveled through all
the points required to get from 150 lbs to 155 lbs.

If you're tracking the amount of hours you sleep every night, you should use a
column chart. Just because you get 6 hours of sleep on Tuesday and 8 hours of
sleep on Thursday doesn't mean you got 7 hours of sleep on Wednesday. The data
isn't continuous.

For market share, that data is continuous - you can't get from 10% market
share to 15% market share without passing through all the percentages in-
between. Therefore, a column chart is very much the wrong way to display that
information.

~~~
jameshart
Area charts differ from line charts though in that they emphasize the
cumulative integral under the line. In your weight example, in general the
total of your weights on each day multiplied by the number of days is not a
meaningful statistic (except perhaps to the operator of the elevator in your
building who is tracking cumulative strain on the support cables). An area
chart makes sense if the product of the x-axis and y-axis units make sense.

Data continuity is a secondary concern; there's no reason not to have a
stepped area chart, which is the union of a set of adjacent bars representing
discrete measurements. And sleep hours per day do accumulate nicely over time,
so an area-emphasizing plot does make sense (sleep hours per day * days =
sleep hours). It lets you look at two parts of the chart and assess 'did I get
more sleep in this period or that period'.

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stevewilhelm
One of the things I dislike about stacked area charts (or stacked bar charts)
is that are in many cases are used to show percentage breakdown over time.

The problem with representing percentage breakdown over time this way is that
it visually eliminates the size of the sample, be it size of market, number of
users, page visits, etc. It is visually implying that the same size has stayed
the same over time.

Take these two charts representing the breakdown of smartphone shipments by
manufacturer: [http://s831.us/1kmFK28](http://s831.us/1kmFK28) and
[http://s831.us/1kmFrEz](http://s831.us/1kmFrEz)

The first displays the percentage of market by manufacturer over time. In this
chart, Apple's performance looks mediocre.

Then look at the second graph that displays the number of units shipped by
manufacturer. Here the amazing growth of the smartphone market is visually
captured along with the breakdown of which manufacturers are driving or
benefiting from the growth.

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dllthomas
There are things stacked charts can show you much more clearly than other
things. For a particular process I'm working on, I have a timing breakdown
rendered as an area chart (not normalized, ordered by total time) that showed
something I'm not sure would have been visible any other way.

My ascii art skills are failing me, and this is going to be hard without
visual aids, but I'll try...

Overall, there was a significant and stable jump from best case to worse case
(not _worst_ case). What was interesting was that a chunk of time the size of
that delta always fell in a single region but it was not always the same
region but always roughly the same amount of time from the start. Since the
process is small scale and kicked off at varying times, this means it was
something asynchronous but triggered by our activity (or activity we were
responding to).

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owenversteeg
Site's down, archive.org link:
[https://web.archive.org/web/20140409154002/http://www.leancr...](https://web.archive.org/web/20140409154002/http://www.leancrew.com/all-
this/2011/11/i-hate-stacked-area-charts/)

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jakejake
I've always felt like I had some deficiency when it came to viewing stacked
area charts. I rarely liked them but couldn't put my finger on why (not that I
really gave it much thought). This article's explanation of our eye's tendency
to see thickness rather than the vertical distance is spot on. I find the
stacked columns way easier to read, although if you had a lot of data points I
agree with several of the other posters that a boring old line chart is going
to be the easiest to read.

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capkutay
Gauges and 3d area charts are other examples of misleading visualizations that
take up a lot of space without deriving much meaning. Why do we keep seeing
them? They're flashy and make my dashboards look like the one my competitor is
using! That's just the world we live in.

After studying data visualization, it's surprising how most popular dashboard
widgets/visualizations are relatively bad at encoding data versus simple
things like sorted tables.

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dsugarman
we use them on internal dashboards and they can be extremely useful. One use
case is keeping track of bad orders, we work on the dropship model so the top
line is our total bad order percentage and each area is the bad orders from a
certain supplier. When the goal is to lower the top line we focus all our
efforts on the largest areas.

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thanatropism
Hahaha. The solution described works if you have t=6. Try having t>>25.

The perfect use case for stacked area charts (but not pinned to 100%) is when
there are many categories, but one is very predominant, and you're interested
in (a) the sum of all quantities and (b) the participation of the principal
category.

Example: a country is mainly reliant on hydropower for domestic electricity;
there are years where it doesn't need any other source (it's still
cheapest....). So we want to track (1) the evolution of domestic consumption
and (2) the share of hydropower (3) which years it hasn't been enough.

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kahaw
I think this more illustrates a problem with trying to generalize solutions.
The final stacked area chart with green at the bottom works perfectly for this
data set. Even the author's proposed solution fails to emphasize the growth of
the green section.

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001sky
To be fair, its 'mis-use' that is the problem here. Like any tool, the right
one should be selected for the job. There are people out there that generalize
this same logic to "charts" without qualification (they prefer tables).

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noswi
Not meta enough. When was the last time you designed the chart for a book or
other static media?

I'd like to think that in this age there's no need to force a static,
unexplorable view of the data to the user at all.

~~~
retroencabulato
Print still exists, you know.

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merusame
Talking about fancy visualisations, you should definitely have a look at
horizon graphs

[http://square.github.io/cubism/](http://square.github.io/cubism/)

~~~
jessaustin
Nice, but I think it would take some time to get used to the "overplotting"
thing. Sometimes it's better to just take up a bit more space for clarity's
sake.

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rwain
Making a stacked graph interactive can help like this one I prepared earlier:

[http://theopenindex.org/](http://theopenindex.org/)

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jessaustin
You don't have to stack it like that:

[http://bl.ocks.org/mbostock/582915](http://bl.ocks.org/mbostock/582915)

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yellowapple
I hate stacked charts, period. I would much prefer a line graph - and with
absolute values rather than percentages.

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misaelm
Stacked charts are no better when trying to compare categories other than the
one closest to the x-axis against each other.

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darksim905
Color me dumb, but that chart/graph made perfect sense to me as it was.

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quotient
Yeah, that's a fair point. These charts are misleading. Then again, if you
generally trust charts for an easy interpretation of data, you're probably
going to be misled anyway. Perhaps I express an unpopular opinion, but the
only way to really get a handle on the data is to _read the data_. (I find it
to be a rare occurrence that a chart exposes --- rather than oversimplifies
--- relationships in the data. They're mostly okay for a cursory glance, but
not for more. In this example, they're not even okay for a cursory glance.)

~~~
hessenwolf
How would I determine if the pattern was linear or logarithmic, whether an
observation was an outlier, or whether two series were related?

A tiny bit ad hominem, but I take it you are not a statistician. The first
thing we do is to graphically illustrate the data, because human brains are so
good at recognising patterns.

It is important to experiment with several variations of display, also
including and excluding outliers and different series, to see if there are
biases that mislead you.

Only then do we come up with a mathematical model to fit.

Actually reading the data line by line can be extremely misleading - because
you can only compare a few numbers at a time, which fails to give you an
insight into the overall variation.

~~~
quotient
I am in fact a statistician. I work in statistics, mathematics, and computer
science. I am often severely frustrated by the oversimplifying and misleading
natures of conventional charts.

I have seen good charts. Yes, they exist, and I actually see them quite often.
It just so happens that the vast majority of charts and graphical
illustrations I see are omitting details at best and dangerously misleading at
worst.

~~~
thanatropism
This is very true.

Reading Tufte carefully, one realizes that (a) he's read more Derrida than
he's willing to admit (there are entire unattributed quotations, probably by
accident) and (b) great charting is an art form, perilously predicated on
someone being both quantitatively educated and visually gifted.

There is no silver bullet but the table, and even then, Simpson's paradox is
always ready to bite you.

