What is measurement?
Updated: Oct 10, 2022
Cross-examination of a CFS scientist on the VIM.
To connect "measurement" in Canadian evidentiary breath testing to "measurement" in the international literature, specifically the International Vocabulary of Metrology (the VIM Exhibit 18), referred to in most international scientific literature on measurement
To define any measurement in Canada, including a measurement for a forensic purpose as a comparison.
To obtain admissions from the CFS scientist as to the applicability of the definitions in the VIM to the matter before the Court and the Criminal Code respecting:
measurement (as a comparison)
Q. Mr. P, as I was driving here this morning, coming up Highway 400 there was a truck at the side of the road at a weigh scales. And the truck at the weigh scales, I could see that the weigh scales – I couldn’t read exactly what the weigh scale said, but I saw something that said 177,000 and then a whole bunch of other numbers flickering. Now that, I take it, would be something that’s operated by the Province of Ontario weighing the measurement of a truck. And I’ll – as measurement. A. I would assume so, yes. Q. So the measurement, when you weigh a truck you’re measuring something called mass? A. Yes. Q. And the measurement said 177,000 something, but the other digits were all flashing very, very quickly. So it struck me that maybe the machine, the instrument that is
measuring the mass of the truck is generating a large number of measurements very, very quickly, and then eventually it’s going to settle on one measurement. Does that make sense? A. Correct. Given enough time. You have to wait for the – I would assume – that you would have to wait or the operator would wait until the – the weight has stabilized, which may be affected by a number of factors. But I’m not an expert in weighing trucks at weigh stations. Q. Well.... A. And when I drove up, I didn’t see any of that. Q. You didn’t see the same truck, I guess. A. No. Q. All right. Now let’s suppose that the number scale settles at 177,500. A. Okay. Q. That’s a quantity. To a scientist, that’s a quantity, 177,500. A. Yes, that’s the weight of the truck. Q. But.... A. Including everything that’s in that truck. Q. Does the word ‘quantity’ have a special meaning in science? A. It’s an amount. Q. It’s a number. A. Yes. Whether that’s volume or weight. Q. And any time that you’re measuring something as a scientist, I gather you have lots of experience as a scientist, in measuring things. A. Yes, a number of years. Q. Any time that you’re measuring something, in science, you obtain a "quantity" but you also have to be
concerned with something called a "unit". Right? A. You’re talking about variability? Q. No, I’m talking about what it is that you’re measuring and how you measure it. I mean, does it make sense that this truck is being measured as the unit of measurement being 177,500 paper clips. A. I would assume it would be kilograms, but.... Q. Oh, kilograms. All right. Now a kilogram.... A. I have no idea, again, what the truck stop is weighing. I would assume it’s weight. Q. Okay. Mass. A. Yes. Q. And if we’re talking about kilograms, a kilogram is 1000 grams. MR. O: I’m – I’m just wondering about the relevance of all this, Your Honour. THE COURT: Well, there’s an analogy developing. MR. O: All right. MR. BISS: Q. So.... A. Yes, 1000 grams is equal to a kilogram. Q. One thousand grams is a kilogram. All right. Now in the international scientific community I understand that there are – well, first of all, can I just ask you. The science of measurement, is that an area of science? A. Well, measurement can be outside of science too. It could be wood working. It could be... Q. Well, let’s talk about.... A. ...any number of different things. Q. Let’s talk about science – let’s talk about
measurement for now, just within science. A. All right. Q. And is the name of the field of measurement science something called Metrology? A. Yes. Q. M-E-T-R-O-L-O-G-Y, not to be confused with meteorology. A. Correct, yes. MR. BISS: Now the – if I could just have the Court’s indulgence – Exhibit 18. I wonder if everybody could just make sure they’ve got a copy of Exhibit 18 and I’ll show Mr. P mine, if the Court doesn’t mind me approaching him? THE COURT: No, that’s fine. MR. BISS: Q. Metrology, definition 2.2. I think there’s a definition there, 2.2 of metrology. Could you just read that definition, please? A. Note, metrology includes all theoretical and practical aspects of measurement, whatever the measurement uncertainty and field of application. Q. Yeah, and there’s a definition, I think, just above it, under 2.2. It says, “Metrology.” A. The science of measurement and its application. Q. Oh. The science of measurement and its application. So, the question is, what’s a measurement to a scientist? In the same document, Exhibit 18, the authors of this document have defined "measurement", and I wonder if you could just read that definition of measurement. That’s at page 16. A. The process of experimentally obtaining one
or more quantity values that can be reasonably attributed to a quantity. Q. Quantity values. A. Well, it says quantity. Q. All right, and does it have any notes underneath? A. Note one, measurement does not apply to nominal properties. Q. Yes. A. Note two, measurement implies comparison of quantities or counting of entities. Q. Yeah. A. And note three, measurement presupposes a description of the quantity commensurate with the intended use of a measurement result. Q. Yeah. A. Comma, a measurement procedure and a calibrated measuring system operating according to the specified measurement procedure, including the measurement conditions. Q. Right. Note number two, can you just read that again please?
A. Measurement implies comparison of quantities or counting of entities. [see notes to 2.1 "measurement in VIM] Q. When an individual has a subject test, on an Intoxilyzer 8000C, is there a comparison? Experimental. A. Is there a comparison made? Q. Yes. A. The instrument is measuring the breath sample that’s provided and then determining the blood alcohol concentration from a sample of that breath. Q. There’s no comparison?
A. Then there’s a comparison of the result that’s obtained to a calibration curve. Q. To a calibration curve. All right. That’s a.... A. And then that result is compared to the second test that’s done 17 minutes or later. Q. Okay. So, the instrument, and we’re getting way ahead of ourselves, in levels of complexity. Calibration curve, I take it, is a fairly difficult concept to explain. A. No. It’s simply a matter of that you have a standard of known concentration, and that you get a response based on that concentration then you produce a curve based on the increasing concentration of that component.
[note that he is talking about a reference standard at time of calibration, not the alcohol standard used as a control at time of testing] Q. But it is a curve. It’s not a line. A. It could.... Q. It’s not a straight line. A. It can be a straight line in some cases, and it can be a curved line in others. Q. Right. A. Depends on what it is you’re measuring and how it’s being measured.
[this is the concept of "linearity" discussed elsewhere in other blog entries] Q. All right. So, let’s.... A. Some are linear, some are not. Q. So, let’s go to what it is that we’re measuring in such a case. And just before we do that.... ...
MR. BISS: Q. So, I just want to go back to another definition. Something called a measurement unit, again Exhibit 18 at 1.1. What’s a "measurement unit"?
[See VIM 1.9(1.7)] A. A unit of measurement. Q. Right. So, can you give me some examples of units of measurement? A. Inches. Meters. Yards. Q. Right. So.... A. Kilograms. Q. All right, I think – I think we’ve got... A. Or smaller. Temperature. Q. ...enough information from that, so maybe a degree Celsius or a degree Fahrenheit would be a unit? A. Or a degree Kelvin, yes.