Talk:Absolute scale

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There's a good description of this concept here: http://stattrek.com/statistics/measurement-scales.aspx?Tutorial=AP

This article could definitely use more sources. Unfortunately, that one won't qualify as a reliable source. Instead, if you could find websites that aren't trying to sell something, like a university, government, or some other such website, that should be acceptable. Zaereth (talk) 23:09, 1 May 2017 (UTC)[reply]

I challenge the claim that these are based on an absolute scale. They are based on standardized tests, which is not the same thing. They are just an agreed basis on which to make an assessment, the very opposite of an absolute scale, which must have a physical/biological reference point.--Murky Falls (talk) 05:21, 3 October 2021 (UTC)[reply]

Have you read the source? Page 96--101 is the chapter on absolute scales. It says that in neuropsychology or cognitive science there are currently two types of absolute scales, with probably the best known absolute test being Progressive Matrices. Outside of cognition or psychology, there are other examples. For example, an EEG is usually read from an absolute scale, where the waveforms are read in comparison to a zero-volt reference, although for some purposes a relative scale is used where background electrical-activity serves as the zero point. I could go on, but I'd suggest just checking the sources (and the internet is a poor source for just about anything, as most really good information is still only available in books). Zaereth (talk) 06:58, 3 October 2021 (UTC)[reply]

I haven't read the source, but your mention of Progressive Matrices surprises me. I can understand an EEG being on an absolute scale going down to zero volts. That sits nicely alongside length starting from zero, the familiar absolute zero temperature, and the delightful concept of absolute time measured from the start of the universe. But a zero score on a Progressive Matrix wouldn't represent zero cognition; the subject might be dead or alive. NebY (talk) 22:20, 4 October 2021 (UTC)[reply]

While the subject of neuroscience interests me greatly, in particular dog neuropsychology (it's fascinating to see how similar they are to humans in many respect yet so drastically different in others; they have a completely different Umwelt from ours), I am by no means an expert. In this case, I just ran across that while looking for some examples to put at the end.

In cognitive science, death would be a poor baseline, as cognition is not necessarily a requirement for life. It's a bit different from the auto-navigation that utilizes most of our brain, in that cognition deals with comprehension and understanding of sensory input. For example, in the study of vision, people with blindsight have an optical nerve that is severed, while the ocularmotor nerves remain intact. While such people can see movement, follow objects, and correct their gaze and vergence, they cannot make any cognitive sense of what they are seeing; it has no light or form or shape or name, just a rough approximation of speed and direction.

As I understand this particular book, the author says that in neuropsychology an absolute scale consist of one that is not based upon any cultural or standardized norms, but rather is built upon raw data without regard to such norms. Unlike most other IQ tests, PM relies on simply a series of puzzles, each with a missing piece. The tested simply fills in the blank. Because it it not based upon any cultural norms or standards of a certain population that change over time, it shows changes in these populations without regard to the changing norms. This is what led to the discovery of the Flynn effect.

Now, that's according to the source, although the source also says that in most instances it is impossible to set a truly absolute scale. Just about any test has to be baselined against some standardized norm, and finding a way to develop more would likely be a benefit.

Either way, I was just looking for examples when I included it, and neuroscience includes more than just psychology; there are also hard sciences of chemistry and electricity. But I have no objection if you'd prefer to remove it, as it is just an example. Zaereth (talk) 00:10, 5 October 2021 (UTC)[reply]

By the way, the concept of "absolute time" made me chuckle. That's making an awful big assumption that time began with the universe. Still by that scale it is certainly possible, give or take a few hundred-million years, so that would be the smallest increments you could achieve, thus making it useless from any real historical context not on an astronomical scale. The thing to keep in mind is that, just like energy, in physics today there is no real concept of what time is. We do not have any picture that time does this or is made of that, and progresses in some certain way. Mathematically, time is simply speed divided by distance. The only time known to truly exist is now, and in some schools of philosophy our own perception of time is merely an illusion of memory and imagination, ie: the brain's interpretation of the Second Law of Thermodynamics (everything changes and some changes are irreversible). But, it's an interesting idea assuming we could ever pin the Big Bang down to an exact moment. Zaereth (talk) 01:23, 5 October 2021 (UTC)[reply]

Thanks for the explanation and fascinating discussion. I don't think we need to remove anything if that part of the source is also referring to EEGs or suchlike; we're not specifying PM. Personally, I think the source's distinction between culturally defined/standardised and absolute measures is a bit different from that in other metrology, where we go from culturally defined measures (cubit, stadia, barleycorn, month) to standardised (metre, second), some from either group describable as absolute. Indeed, I'm very attracted to the idea that the Flynn-effect increase in PM scores does reflect a culture that presents information graphically more often than it did in say, the mid-twentieth century, more often partly because it's no longer necessary to employ graphic artists to present data and better partly under the influence of Tufte et al, who taught us to spot some of the worst cases.

Yes, a scale where the present is at about half an exasecond from the start of the local universe might not be so useful and as you say, now is the only known time. Awkwardly, as Before Present radiocarbon dating uses 1950 as year zero, now is currently 71 years After Present. NebY (talk) 17:20, 8 October 2021 (UTC)[reply]

Well, like I said, I was just going by what the source said. I have to trust that a book on neuroscience is a far better judge than I when it comes to cognitive tests.

When it comes to time, that's an even bigger mystery, even to the experts. Much of Einstein's Theory of Relativity is based upon his study of time, or in his case, the concept of simultaneity. The thing about time being a function of speed and distance makes it a problem, because, as Einstein pointed out, there is no such thing as absolute speed. To judge speed, we need a fixed reference frame, and in the universe nothing is fixed. All you have to go on are the relative reference frames. For example, here in Anchorage I'm moving at about 530 mph, just spinning with the Earth. If you're near the equator, it's closer to 1500 mph, but the only way to tell the difference is that the sun moves slower across the sky up here. The Earth is moving at some 48,000 mph around the sun, while the sun is going some 150,000 mph around the galaxy. No one knows just how fast the galaxy is hurtling like a frisbee through space. But here in my own little reference frame, I'm not moving at all.

Take the Big Bang, for instance. The origin of the universe cannot be tracked down physically, like making a simple measurement of length. We can get a relative estimate of when it occurred from the microwave background radiation, which is ultimately based upon the speed of light and working backwards. The same really with astronomical distances. You can get a rough approximation of distance and time, based on the speed of light, but that's about as precise as you can come.

The point of having an absolute scale is to avoid imprecision that a relative scale can cause, and this is probably most apparent in deep vacuum or deep cold measurements. (Kelvin was a pioneer in both fields, and, along with Edison and others, quickly saw the need.) For example, when you try to take deep-vacuum measurements, or other high-precision measurements, with a normal gauge, you start to get wonky readings due to pressure fluctuations in the atmosphere. There is a level of precision you can't reach using a simple Bourdon gauge or manometer. A gauge built on an absolute scale will give unchanging readings regardless of changes in atmospheric pressure. That's why torr is almost always used in the field of lighting, and atmospheres in aeronautics. Then again, in some instances a relative scale is better. For example, in measuring blood pressure, an absolute scale is not nearly as important as the difference between blood pressure and the back-pressure provided by the atmosphere, which better indicates burst pressure. Blood pressure is almost always measured using mmHg (the same increments as torr, but one is absolute and the other relative, ie: 120/80 mmHg would be read as 880/840 torr).Zaereth (talk) 21:57, 8 October 2021 (UTC)[reply]

Got to disagree about pressure. Absolute pressure sensors and gauges are harder to make and more liable to deterioration, and inappropriate in many fields - you wouldn't want to measure tyre pressure with an absolute pressure gauge. Or take flow measurement with venturis and orifice plates. The critical measurement is the differential pressure across the device, often a small fraction of the fluid's absolute pressure. It's fairly easy to make the dp sensors, manometers or gauges, and they're far more accurate than taking the difference beteween two absolute devices. You might also want to measure the pressure of the fluid if it's compressible, but that might be being controlled anyway or at least not fluctuating much. If you do want to adjust for it, then you might still find that atmospheric pressure changes are going to matter so little, a gauge pressure sensor and a constant suffice. Horses for courses. NebY (talk) 17:53, 14 October 2021 (UTC)[reply]

Like I said, in some measurements, a relative scale is better. It all depends on what you're trying to measure for. If it's an altimeter on an airplane, then you'd want an absolute gauge. If you're building a flashtube or neon sign (which I have), then absolute is the way to go. If you're taking barometric readings, an absolute scale is a necessity. There's a reason people like Kelvin and Edison used the torr scale. For blood pressure or tire pressure, hydraulic pressure, etc., then a relative scale is by far the better choice. Likewise, for some EEG tests, sometimes an absolute scale is best, while in others a relative scale is better. It all depends on reason for the test, the parameters, and the end goal. Zaereth (talk) 18:11, 14 October 2021 (UTC)[reply]

Oh, and just to bring this full circle, in case the analogy wasn't readily apparent, the discovery of the Flynn effect was due to having a scale where the goalposts weren't constantly changing, which is what I think the author meant by calling it absolute. And for those who would point out that the speed of light is always the same, that's exactly the problem. It's always the same no matter what your reference frame, what direction you look, or how fast a person is moving, so as goalposts go it really tells us nothing about our own speed or direction. (See the Michaelson-Morley experiment, aka: the greatest failed experiment in science.) Zaereth (talk) 01:21, 13 October 2021 (UTC)[reply]