Amnesty Hearings — Durban — 2000-07-27

S R NAIDOO: I think we, it's a play on words, there's nothing that you can rule out.

MR VISSER: We're not playing with words, Doctor Naidoo ...(intervention)

CHAIRPERSON: If I could just ask a question just for my own clarity, and correct me if I'm wrong.  I'll tell you what I understood, was that you take the femur, you do the measurements of the femur and the other long bones and you apply Lundi's formula and you come up with an answer and in your case you came up with this parameter of 1,35 to 1,42 and you said that there is a 95% confidence level.  My understanding was that that 95%, or alternatively the remaining 5%, didn't relate to figures.  In other words, it wasn't that 1,35 to 1,42 was 95%, it might be 5% either way or either way.  My understanding is that 95% of the population of that particular group would fall in that range.

S R NAIDOO: That's right.

CHAIRPERSON: You might however get somebody with a very short femur and a long torso who might be 12 centimetres or 20 centimetres, a sort of freakish type growth, who would fall in the 5%.

S R NAIDOO: That's correct.

CHAIRPERSON: And that person falling out of that 95%, didn't have to be within 5% of 1,42 or 1,35.

S R NAIDOO: That's so, that's correct.

CHAIRPERSON: That was my understanding.  It didn't relate to figures, that 95% and 5%, to the measurements.

S R NAIDOO: That's right.  It's an expression of the population ...(intervention)

CHAIRPERSON: ...(indistinct) to probabilities of ...

S R NAIDOO: ... that will into that, yes.

CHAIRPERSON: Yes, that's what my understanding was, but anyway ...

MR LAX: I thought I'd specifically canvassed that with you, because that's how I understand these sorts of statistical tests where a sample of people, a hundred individuals of a particular group are taken, they represent and mean of the population and what I understood when you said 95% confidence, from my little knowledge of statistics, that means that that's a 95% sample of the population for which those figures are then valid with, given the fluctuation that's how statistics work.

S R NAIDOO: Yes.

MR LAX: And that there's in fact, this confidence represents the 5% of the population who fall outside of that sample.

S R NAIDOO: Yes.

MR LAX: In other words, the sample didn't - you never sample for 100% of the population, you'd have to do every single individual.

S R NAIDOO: That's right.

MR LAX: So statistically that's how it's done.

S R NAIDOO: Yes.

CHAIRPERSON: I'm sorry, Mr Visser, I can't seem to find anything in my notes.  I'm not saying that it wasn't, I just haven't recorded anything to the effect there.

MR VISSER: Chairperson, may I explain myself?

CHAIRPERSON: Yes.

MR VISSER: I'm giving the Doctor the benefit of the 5%.  I hear everything that Mr Lax says and what you said and that's certainly as I understood it.  I have now asked him whether - I've now assumed that it's also applicable to the range, to give a further leeway, Chairperson.  It's only on that basis.

CHAIRPERSON: Yes.

MR LAX: You see Mr Visser, the problem is this, is that 5% is not adding on 5% of the fluctuation in height, you can't take those - let's take 1,42 as the extreme, add on 5% and then get the external mean so to speak, or the maximum.

MR VISSER: Yes, I'm perfectly happy with that, Doctor.  So on that basis I will put to you that if we know that Ms Kubheka might have been 152 centimetres, your maximum of 1,42 is approximately 10 centimetres, well precisely 10 centimetres out.

S R NAIDOO: You're right.

MR VISSER: And on the lower level, your minimum of 1,35 would be approximately 17 centimetres out.

S R NAIDOO: Right.  But you'd ignore the lower level ...(intervention)

MR VISSER: Alright, well let's ignore the lower level, let's talk about the 10 centimetres.  ...(intervention)

MR LAX: Sorry, can I just ask this?  Why do we ignore the lower level?  Just so we understand it.

S R NAIDOO: Well because when you're looking at the deviation from normal, you look at simply the difference from the - if you - it's simply this, if you're standing outside a room you say you're standing, if you're standing one metre away from the room, you're standing one metres away from the nearest wall, not the other wall on the other side.  You understand what I'm saying?

CHAIRPERSON: Yes.

S R NAIDOO: Very briefly.  You know, I'll just reiterate that this doesn't - it's very, very difficult to say that it amounts to an exclusion, it's simply a matter of confidence in what we accept.

MR VISSER: Yes, alright ...(intervention)

S R NAIDOO: I would say also that 20 centimetres difference was a lot.

MR VISSER: Yes.

S R NAIDOO: 10 centimetres difference is half of 20, it's not that much.

MR VISSER: Well it's half of it.

S R NAIDOO: It's - you know, it's all one can say.

MR VISSER: Well Doctor, ...(intervention)

S R NAIDOO: If I may deviate slightly, the figure you're giving me, you're giving me a figure of 1,52 for me to answer with, even the 1,52 is an assumed figure, is it not?

MR VISSER: You don't have to worry about the evidence.

S R NAIDOO: Okay, right so ...(intervention)

CHAIRPERSON: Just one more question, a general question.  Would the age of the bones have any significance at all?  In other words, if you've got a skeleton that was three months old and one that was thirty years old, or whatever, would the age of the bones make a difference in the application of Lundi's formula in the measurements, etcetera?

S R NAIDOO: Not much.  There's said to be shrinkage due to heating of bones.  If they were baked they may shrink somewhat, but if it's not heat, changes of heat, it shouldn't really make a difference.

CHAIRPERSON: It wouldn't have a significant affect at all?

S R NAIDOO: That's right.

CHAIRPERSON: Thank you.

MR VISSER: Thank you, Chairperson.
	I'm not going to ask you too many questions because I'd like to speak to somebody about your evidence, Doctor Naidoo, but can I just put it to you that even on the 1,52, the probabilities of Mrs Kubheka being the person to whom that skeleton that you examined belonged, must be very low.  On your formula, because otherwise, what does your formula mean?  What does it help?

S R NAIDOO: It's a guide.

MR VISSER: Yes, well ...

S R NAIDOO: A guide.  What's it's pointing is pointing to a considerably short individual.  And for that reason I simply - the conclusion from that stature calculation was that it points to a considerably short individual.  That is all really that one can actually say.

MR VISSER: Yes.

S R NAIDOO: If you try and say ...(indistinct) it's based upon that interval that I get and you're looking at now probabilities of exclusion based upon the distance away from that range, I think you are taking this to ...  I think this inquiry is taking this to an extreme that would be scientifically inappropriate.  What I'm saying is - I'm coming back to this, I'm watering this down - not watering this down, I'm reading this back to what does stature estimation actually mean?

MR VISSER: Yes, I was just going to ask you that.

S R NAIDOO: It's a guide, it's a guide.

MR LAX: Sorry, what does what mean?

S R NAIDOO: Stature.

MR VISSER: And within what parameters is it a guide and when is it no guide no longer?  I mean how far do you have to go for this Lundi's formula to have any meaning for a Court of Law or for a Commission of Inquiry?

S R NAIDOO: I'm not too sure if I understand the question.

MR VISSER: Well you say it's just a guide.

S R NAIDOO: Yes, yes, and that's all, that's all it is.

MR VISSER: Within what parameters is it a guide?

S R NAIDOO: Within - well what I'm saying is, the interval that I give gives you an idea as to the general height of that person.  That's all the guide tells you.

MR VISSER: Chairperson, I see my attorney has another question for me.  Chairperson, I don't think I can take it further at the moment, thank you.
NO FURTHER QUESTIONS BY MR VISSER