Day 252 - 20 May 96 - Page 10
1 period of several hours. What they found in this report is
2 that the ability of the blood vessel to respond to this
3 total constriction was reduced by 50 percent by the high
4 fat meal. They also state that with the fat free meal
5 there was no significant change.
6
7 Now, I have quite a number of problems with this. I mean,
8 if this was sent to me as a full paper as a referee I would
9 have an awful lot to say about it. The first thing would
10 be that looking at the variants we have here after a period
11 of 3 hours the activity of the vessel to expand in this
12 wholly unphysiological way was reduced by 50 percent to a
13 value of 9.3, but we also have a standard deviation beside
14 it, and this is looking at the statistical treatment of the
15 data, the standard deviation is ten times higher, which is
16 extremely high. Now, I did a quick calculation to decide
17 what this meant in terms of variation, because the standard
18 deviation is a measurement of the variation about the mean
19 variant, and this means we would have values as low as two,
20 which means a huge effect on the blood vessel, or it could
21 be as high as eighteen, which means that practically
22 nothing happened at all---
23
24 MR. JUSTICE BELL: I think I will need some explanation about
25 this.
26
27 MR. RAMPTON: Well, my Lord, I would rather the witness explain
28 it because if one takes the starting point as 20.4 -- is
29 that right?
30 A. Yes. It is simply a matter of statistics and I may
31 say, your Lordship, that I am not an expert in statistics
32 myself. But the standard deviation is a measure of the
33 variation about the mean value for a population that is
34 being measured. Now, normally this is around ten percent.
35 So that for a value of 9.3 one might expect a standard
36 deviation of about one. In this case the standard
37 deviation is 7.5. It is almost as large as the mean
38 value. What that really is saying is, there is a huge
39 variation in arriving at that mean, a huge variation in
40 these 5 individuals. They responded in rather different
41 ways.
42
43 MR. JUSTICE BELL: But the one is -- I thought you would expect
44 a deviation of about ten percent?
45 A. Yes. So, in fact, for a value of 9.3 plus or minus
46 0.9 would be a nice figure to have.
47
48 MR. JUSTICE BELL: Yes, but it is percent, not plus or minus a
49 figure?
50 A. No, the percentage is referring back to the percentage
51 expandability of the vessel. The measurement that has been
52 made is a measurement of the percent to which the diameter
53 of the blood vessel increases when you put a cuff round the
54 arm and prevent the blood from flowing out again. So the
55 vessel expands like a balloon and the maximum expansion on
56 baseline is 20 percent.
57
58 MR. JUSTICE BELL: So you say it is--?
59 A. What I am saying is--
60
