Qualitative vs Quantitative measurements

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Spectrum
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Qualitative vs Quantitative measurements

Post by Spectrum » Fri Jul 27, 2018 4:24 pm

I just came across this article from the BBC during lunch today. We've had quite a few discussions on common.. and uncommon! measurements around here and was curious about thoughts. Some of the items that are listed as qualitative in the article don't sit with me quite right.. I thought that they were well defined.

Any favorite measurements?
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Batgirl III
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Re: Qualitative vs Quantitative measurements

Post by Batgirl III » Fri Jul 27, 2018 9:33 pm

I generally find "qualitative" anything to be annoying as heck, give me nice objective, empirical, and falsifiable objective data... or at least standardized units. This was the reason I wore boy's jeans through almost all of my teen years. I have no idea what the hell women's clothing sizes are... Size 2? Size 12? Size 00!? TWELEVE WHAT!? Give me some units, you motherfriggin... Arrgh! Still makes me angry. Boy's jeans were so much easier to find in a size that I know would fit, sure, some brands were cut a little more generously or a little more narrowly than other brands, but for the most part a 24" waist was a 24" waist was a 24" waist.

My favorite unit has got to be the "ton," and by "ton" I actually mean the 24,601 different definitions of the word that are all in common use and often have vastly different meanings. Oh, and by "favorite" I mean "thing that bloody annoys me approximately ninety times each week." Thankfully, most of the planet uses the metric system and most of my time is spent dealing with metric tons / tonnes, tonnage, or displacement tonnage (no, those aren't the same thing and they aren't even measurements of the same thing).

Of course, every now and again I have to dig into some very old contracts and insurance records. These usually use old Admiralty units and are often attached to cargo manifests that also are filled with old Imperial measurements... and I swear to you, they all sound like made-up names for families of Hobbits: gallon, firkin, kilderkin, slug, barrel, hogshead, rundlet, puncheon, pipe, butt, tun... dram, stone, hundredweight... furlong, fathom, link, rod... perch, rood, acre... fluid scruple...

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BriarThrone
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Re: Qualitative vs Quantitative measurements

Post by BriarThrone » Sat Jul 28, 2018 10:49 am

I watched a video series by a YouTuber who I respect very much, where she tried to educate her audience on how qualitative evidence could be valid and useful. At every step, I stopped and thought "Could bias or willful ignorance influence this particular step meaningfully? ...yeah, it really could." If you are using it in good faith to try to direct your quantitative research, maybe it has an internal use for your studies, but broadly, no, qualitative data is too open to interpretation. You will generally find what you were expecting to find, because that's what catches your attention most.

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Beleriphon
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Re: Qualitative vs Quantitative measurements

Post by Beleriphon » Thu Aug 02, 2018 9:11 pm

BriarThrone wrote:
Sat Jul 28, 2018 10:49 am
I watched a video series by a YouTuber who I respect very much, where she tried to educate her audience on how qualitative evidence could be valid and useful. At every step, I stopped and thought "Could bias or willful ignorance influence this particular step meaningfully? ...yeah, it really could." If you are using it in good faith to try to direct your quantitative research, maybe it has an internal use for your studies, but broadly, no, qualitative data is too open to interpretation. You will generally find what you were expecting to find, because that's what catches your attention most.
As the article points out, qualitative measure are valuable. The Richter scale for example is qualitative, it measures the qualities of what an earthquake does, rather than the actual force of the earth moving. The EF scale of a tornado is also qualitative, it measures the end result rather than the actual qualities of a tornado.

There are other ones as well, which are all valid. The Rohn scale for example tries to use math to equate a disaster to a number. A fictional example is Justice League's has a scale for threats, with guys like Ocean Master being Alpha Level (I'm assuming that's top of the heap, I couldn't find a reference to the full scale anywhere).

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Batgirl III
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Re: Qualitative vs Quantitative measurements

Post by Batgirl III » Thu Aug 02, 2018 9:19 pm

Qualitative measures are only useful if the people using them understand that they're not quantitative. Far too many people either intentionally obscure the difference or are absolutely ignorant that there is a difference. Watch C-SPAN sometime.
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Beleriphon
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Re: Qualitative vs Quantitative measurements

Post by Beleriphon » Mon Aug 13, 2018 5:30 pm

Batgirl III wrote:
Thu Aug 02, 2018 9:19 pm
Qualitative measures are only useful if the people using them understand that they're not quantitative. Far too many people either intentionally obscure the difference or are absolutely ignorant that there is a difference. Watch C-SPAN sometime.
I tend to agree, but it really depends since there are very clear qualitative scales that are useful. Frozen, cold, lukewarm, warm, hot, boiling for example all tell us something about the temperature of a substance. If describing water I know which ones I can put my hand in, use to make tea, or drink comfortably without knowing that that Frozen is 0 degrees C and boiling is 100 degrees C (assuming sea level of course). In much the same way a quantitative scale is only helpful is the values are relevant or useful, telling me that a box is 30cm x 30cm x 30cm is useful. It is exact, but I need to know if I can get a loaf of bread in it, so the only quality I care about is whether its larger or smaller than a loaf of bread.

Now, I'm sure you'll ask what size is my loaf of bread? It doesn't actually matter, so long as the loaf of bread I'm making fits in the box. Since I'm a simple home cook I'm just eyeballing the size rather than using mass production to produce loaves that all weigh exactly the same and all have the same measurements, but that has to with economy of scale rather than the inherent nature of bread loaves.

Lets try one that looks quantitative but isn't. Betelgeuse is roughly 700 times the diameter of the Sun. That's using some numbers, but its comparing the quality of one star to another to describe the former. For a quantitative measurement of Betelgeuse we would want to say that Betelgeuse is approximately 600 million miles in diameter. Knowing exactly how big a star is gives us lots of useful information that can lead to all kinds of derived information, but it doesn't necessarily help us get a grasp on complex subjects.

Its when you start using a qualitative scale instead of a quantitative scale when the quantitative measure is what you need. For example when making bourbon I need to know that alcohol boils at a 80 degrees C, and water at 100 degrees C. 80 or 100 is still too hot to put my hand in or drink, but isn't going to help me distill bathtub gin.

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