For any measurement, you need a scale, and a frame of reference, if you have growing kids it’s easy enough, the frame of reference is the floor by the door frame, and the scale is the pencil on top of the kids head every birthday, et voila, you have a rough guide to how tall little Johnny was at 3, 4, 5, 6, 7, etc
Tape measures and verniers and stuff, it’s all straightforwards provided you do not want too much accuracy, the zero end of the scale is the frame of reference and the scale itself be it imperial or metric is the amount you are measuring in, because the little Johnny on the door frame wasn’t measuring anything in a scale, just absolute marks, no ratios in between which you get if you measure in something standardized like metric or imperial.
I can go across the road to my local river and hammer a long steel bar into the bed, and if I graduate the bar I can see if the river is higher or lower than yesterday.
Similarly I can go down the road to the sea and watch the tide come in and out twice a day, a rise and fall of between 20 and 30 feet depending on various factors… including atmospheric pressure on the day.
Of course wave action makes measuring sea height difficult if I am trying to be accurate, and if I am trying to be *really* accurate it get very difficult because you have to start asking questions about tidal deformation of the crust, tectonic and geologic motions, and so on and so forth, and the definition of really difficult here is that there are several things all of which can vary by about the same sorts of numbers as the numbers you are trying to get for accuracy.
Then you go back and look at how measurements are being taken, eg radio/radar pulse timings from satellite referenced yadda yadda and the penny drops, you aren’t directly measuring anything, you are counting time for an event, and how accurate is that when you add that into the variability of the sea surface and waves reflecting the beam to be timed back to the source?
And you wonder why maritime chart data is constantly being updated, and topographical geographic data is constantly being updated, and it turn out that a large granite outcropping down the road from me that has been there for several million years, was actually about 6 feet wrong in height, and adjustment / error of around 0.3%, with respect to “sea level”, because lasers could measure it more accurately than simple optical verniers for triangulation.
I’ve got a 25 buck laser tape measure thing, for what it does, which it does up to around 40 metres, it’s fucking awesome, it even has some pythagoran triangulation so it can take two measurements and calculate the third side of the triangle.
It has a claimed accuracy of sub millimetre levels, and when I have tested it on objects a bit less than 2 metres long where I know the actual dimension to 0.1 mm or better from another source, I can say that the laser jobbie was always within 1 mm of correct.
Perhaps at 25 metres that might drop to 10 mm (partially because of the user error) and if so in reality I’d say that was more than good enough for 99.99% of applications…. I can’t see anyone using a 25 buck laser tape to measure and cut a 747 wing strut for example, but for buying bricks or skirting or wiring or paint or general carpentry, more than good enough.
But, when you try to tell me that sea levels down the road have been rising at an average of 0.8 mm per year, I know for a fucking fact you are talking complete fucking bollocks, simply because the shit you are using to measure it a/ isn’t good enough and b/ is constantly changing, a local sea level rise of 80 mm or 3.14 inches over the past 100 years *vastly* exceeds any accuracy that you can reasonably claim, the modern tidal gauges aren’t that good and aren’t corrected that well, 100 years ago it was a line on a stick, you’re talking fucking bollocks, and by definition since this is a subject you are claiming to be a specialist expert about, you absolutely have to know that you are talking fucking bollocks.
A SCIENTIST would tell you that taking instrumentation from 20 years ago forwards, because nothing before that was good enough, the inherent variables in the system exceed any theoretical accuracy in the system, so you really should not be attempting to measure anything to a level of accuracy greater than integer inches, and even then you have to be bloody careful… as in expect to see changes and do not try to read too much into those changes.
I have a set of rarely used bathroom scales, they are electronic, they have never been calibrated, but they give readings accurate, allegedly, to 100 grams, or 0.1 litre of water, about a quarter or a pint, or a cup of tea, or a piss, or a very small shit.
If I have a travel allowance of 25 kg and I put a packed suitcase on them and it says 23.9 kg I’m good to go and no excess baggage charges, beyond that, I wouldn’t trust them.
But, back to measurements, you need, as discussed, the reference, the zero, the floor, the point from which you measure…. and you need to be as accurate and as consistent as possible with this reference point, else everything else you do is bullshit.
Which is why “since records began in 1986” a tactic beloved of government both local and national is nothing more than proof positive that everything that follows is nothing more than a complete lie and fabrication.
Nowadays I almost never see a graph where both the X and Y axes are labelled (s0 you can see what the scale is, and if it is linear or logarithmic) , and where both the X and Y axes have an origin a zero.
I used to know a guy who worked in finance and used excel and the charting feature every day in anger for work, he freely admitted that he spend 0 minutes every day looking at the raw data, and all of his working time messing around with graphy types and graphy colours and graphy axes scales to achieve an end result, and the end result was always something that made a point clearly, look for this line is diverging from this line.
Yeah, I get it, he is trying to highlight a given point and he doesn’t really care about the rest of it, but then again, I have seen fabulous tits on a psycho smelly swamp thing unfuckable bitch, and if all you ever looked at was a close up of some great tits, you would just be conjuring up visions of some hot sexy mama and by the way what’s your number baby….
Back when I was in school the only way you could avoid a zero mark was to show two graphs side by side, one a proper one with zero origin axes, and next to it a detail one showing how one line diverged from another… I can still remember the actual experiment, three fine wires, one copper, one silver, one aluminium, all wound around glass cores in a glass box, all the same length and diameter, and special physics class bench ammeters and voltmeters and shit, which you’d have to test and calibrate before you could trust them… and then you could go and get your results, and if you weren’t *really* careful your margin of errors exceeded the theoretical differences is measurements.
At the end of the class the teacher used his much better instruments, he got closer to theoretical answers, but it still wasn’t textbook, next class was chemistry, go and ask the chemistry teacher, he said, how you can tell what those wires are made from, because so far you’ve been taking my word about composition and dimensions…
Typically we never did get “answers” out of any of those teachers, everything was always a best empirical estimate with a whole lot of unknowns to think about.
Mighty car mods, a youtube channel with some useless australian bastards playing with cars, did a thing about a 20 buck fleabay tuner chip, and here we are at the dyno ripping our car wiring apart, and here we are theorising about what the chip might do, and here we are with the dyno results.
nah mate, for a 20 buck tuner chip #1 is you characterize it electrically, then you depot it and see what is actually inside, and then you take discrete components to do what you theorise the chip might do, eg small resistor on the MAF sensor circuit to boogie the ECU tables, then run the vtec bitch on a few tankfuls of 105 octane.
A 25 minute video and a thousand bucks down the drain to “prove” that a 25 buck ebay tuner chip is shit, easier to hold it up and say if you buy this, you are a stupid cunt, and go on to something interesting, like how good the SAE calibration and adjustments on the dyno rig are, and what you can and can not tell from a dyno run.
This is fucking bollocks
This is less bollocks
But it is still missing important data, like when plastic came in, the 73/74 opec shit, when the gold standard was abandoned and fiat came in, and so on.
little Johnny and the marks are still there, but instead of little Janey walking up to the door frame and doing the hand to mark the height thing to compare, she starts measuring the height of the mark in inches, then millimetres, then the floor is lowered, then from the door handle up, then it’s inflation adjusted for girls being shorter than boys, and before you know it it is just marks on a door frame and complete fucking bollocks.
The house / flat I am living in now was built before that second chart started, and as near as I can measure the original image is 55 pixels high per 20k price, so 370 quid a pixel, and the darker line itself if 9 pixels high, so 3,750 quid, which was an appreciable fraction of the whole house price back in 1952, but even so, you can use this chart to “prove” that apart from a few shaky years in the 90’s, house prices can only ever go up… with a chart that starts in 1952… it’s like a chart showing that a coin flipping machine is throwing ever more heads and less tails, you can “prove” that the odds are no longer 50/50, you just set the start and end dates to exclude anything problematical at the start date and to include anything projected that makes your point at the end.
According to quickbooks, projections for the next financial year for my business are fucking great…
According to me, I have no idea if I am going to get *any* work in the new year. Not for sure guaranteed here is the fucking money boy.
It all depends how you measure, and where you measure from, I tend to count jobs that have been done and paid for and the money is in my bank, everything else is bullshit.