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

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