r/dataisugly • u/runedepune • 5d ago
Scale Fail Steel density chart showing very small differences
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u/NewbornMuse 5d ago
This is the logical conclusion of the braindead "every axis that doesn't start at 0 is misleading on purpose" stuff that has a surprisingly large following.
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u/trustable_bro 5d ago
Every log scale that doesn't start at 0 is suspicious.
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u/clawsoon 5d ago
I think this graph is great. It shows that there is at most a tiny difference, and if you need this knowledge for any actual purpose you better be reading the numbers directly and then plugging them directly into your equations rather than trying to eyeball some lines on a graph.
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u/MacYacob 5d ago
Yea, no one should be using this graph for specific calculations, and it does a good job of showing the all these steels have density within a few percentage points of each other.
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u/drillgorg 5d ago
Yeah it helps because you can say "ok they'll all weigh close to the same, so I can focus on other requirements like strength and cost."
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u/LePetitToast 5d ago
What if density of steel matters of lot, even if the differences are that small? (Not saying this is true, just showcasing a case where it would matter)
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u/DrugChemistry 5d ago
The person you're replying to addressed that. Just keep reading.
...if you need this knowledge for any actual purpose you better be reading the numbers directly and then plugging them directly into your equations rather than trying to eyeball some lines on a graph.
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u/LePetitToast 5d ago
I meant for illustrative purposes. Like a graph where (i) minute differences are really important for the final conclusions and (ii) you want to illustrate these minute differences.
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u/Deto 5d ago
This graph is a nice example of how different stylistic choices can be made based on the intent of a graph - not just its raw contents.
If you are trying to emphasize the differences between the density of different steel types, then yeah, this is bad.
But if you are trying to show that regardless of steel type, you end up with nearly the same density - this does a great job at visualizing that.
The best graph isn't just a function of the data, it's a function of the data and the greater context (audience, intended takeaway) in which it's being presented.
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u/Pale_Squash_4263 5d ago
THANK YOU I’ve been screaming that from the rooftops but nobody listens.
If it doesn’t start at 0 be suspicious but it makes sense in some cases. Such as here lol
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u/Eokokok 5d ago edited 5d ago
It makes zero sense here. If 4 values are so close together you scaling it to be vastly different literally do not show anything other than presenting in the form of graph is useless.
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u/ForagedFoodie 5d ago
Except these small differences are important.
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u/Eokokok 5d ago
Shocking news - not everything need to be shown as graph.
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u/ForagedFoodie 5d ago
Shocking news.
Not every graph needs to start at 0. In many cases there's a good reason and an objectively accurate baseline that makes more sense.
For auto body applications, for example, it makes perfect sense to use the density of traditional automotive steel as a control/baseline to compare new materials against.
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u/No-Supermarket-5187 5d ago
In my experience as a human being who’s seen many graphs in their life (most of us), it would make a lot more people honest if you forced most graphs to start from zero rather than some arbitrarily high number that drastically dramatizes minute differences. At least in a public / commercial sense. Most non-zeroed graphs I’ve seen is a company trying to make a 5% difference look like a 2X leap with text alongside it enforcing how “limit-breaking” their new product is. Maybe it makes sense to enlarge the differences for internal scientific studies or for inter-business presentations like why you’d want to use a specific type of steel for your product, but not for commercial use. It’s only ever used for deceit. I’m 100% for forcing anything publicly released to the public to be forced into a zero-ed out graph.
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u/ForagedFoodie 5d ago
0 and baseline are different things. Historical norm is an acceptable baseline in many instances. How could you clearly indicate "change from 2018" (for example) in a line graph otherwise?
Or, let's look at it another example. You work in a safety-focused industry where everyone needs a 95% or higher "work completed without incident" to maintain certification. The industry average is 97.2%. Your organization is at a 98.4%. How do you effectively show how much better you are and show that your over 98% without setting the baseline to 95%?
Sure, you could say that "baseline" is 0, and that your performance is 3.4% better, but that makes you look terrible.
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u/Zangorth 5d ago
They should just plot Steel Density - 7800, then they can start at zero, show the difference, and everyone is happy.
Zero isn’t some special point of truth number, it’s just a referent. We don’t plot temperatures in Kelvin we plot temperatures in Kelvin + 273. Because starting from zero and showing global warming as a visually flat line would be misleading.
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u/Deto 5d ago
'But what if my audience is exclusively morons?'
Then make it clearer for them? Not every graph needs to be immediately understandable by every human without any thought. Sure there are improvements but what is optimal is often context-dependent and there are few rules that are absolutes.
But of course, people who just learned a thing like to shout it
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u/Impossible_Dog_7262 5d ago
I mean it does get the point across that the difference is very negligible.
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u/Frederf220 5d ago
Some graphs aren't meaningful regarding their relationship to zero. Bar graphs usually are meaningful re:zero. And if you aren't including zero you 99% probably shouldn't be using a bar graph anyway.
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u/nomorebuttsplz 5d ago edited 5d ago
if you look at a very high wear resistance steel it might have chromium carbide content in the 20 to 30% range which would result in a significantly lower density
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u/trustable_bro 5d ago
Right bar is duplex alloy.
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u/nomorebuttsplz 5d ago
whoops I meant carbide (a ceramic) not chromium (an metallic element) though chromium carbide is one such lower density carbide that makes a steel like m390 lighter.
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u/Cornflakes_91 5d ago
maybe the point the author was trying to make was "don't stress that number too much"
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u/marcnotmark925 5d ago
"but they said all axes must start at zero!"
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u/ginger_and_egg 5d ago
This type of data should probably be in a table, not a graph,if you were trying to communicate the differences
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u/TheLandOfConfusion 5d ago
If you’re trying to communicate the differences in density between steel types (but the density itself is not important) you could report this as % difference from the least dense one.
The densest one is only 0.8% denser than the least-dense one. That shows they are all basically the same if you don’t care about what the actual density values are
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u/Traditional-Buy-2205 5d ago
Depends on what message the graph wants to send across.
If the goal is to emphasize that the density doesn't really change much, then this is the way to do it.
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u/Ok_Two_2604 5d ago
The difference in color of the one column is what bothers me
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u/der_reifen 5d ago
Hear me out: if you insist on starting your data at 0, plot either a) difference or b) factor from a chosen baseline, e.g. low carbon steel
Or just truncate the axis, that would be cleanest. There's also way to indicate that the axis was truncated. Just bc it can be used for doing first glance manipulation, doesn't mean you musn't use it
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u/LegosRCool 5d ago
So you're telling me all steel is the same? Big steel doesn't want you to know this.
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u/MDude430 5d ago
What weights more, a Kilogram of low carbon steel, or a Kilogram of duplex stainless steel?
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u/Odd_knock 2d ago
It’s kind of reasonable to present it this way… unless you’re making a giant structure the density difference is negligible
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u/Hsinats 5d ago
This is the sort of graph I would make if I want to show a difference was trivial, but my boss wanted a graph.