Subjectivity and bias in DNA analysis

[Paul Nutteing (valid email address in post script )]

Shame they did not pass their article to a technical reviewer
"All the peaks should be in pairs in this DNA profile" is wrong ,
there can be homozygosity or trisonomy (one or three alleles)
(Itiel Dror, I now see, took up my suggestion to him of turning his
attention
from dermal fingerprints to DNA fingerprints)

http://www.newscientist.com/article/mg20727733.500-fallible-dna-evidence-can
-mean-prison-or-freedom.html
".... We took a mixed sample of DNA evidence from an actual crime scene- a
gang rape committed in Georgia, US- which helped to convict a man called
Kerry Robinson, who is currently in prison. We presented it, and Robinson's
DNA profile, to 17 experienced analysts working in the same accredited
government lab in the US, without any contextual information that might bias
their judgement.

In the original case, two analysts from the Georgia Bureau of Investigation
concluded that Robinson "could not be excluded" from the crime scene sample,
based on his DNA profile. (A second man convicted of the same crime also
testified that Robinson was an assailant, in return for a lesser jail term.)
Each of our 17 analysts independently examined the profiles from the DNA
mixture, the victim's profile and those of two other suspects and was asked
to judge whether the suspects' profiles could be "excluded", "cannot be
excluded" or whether the results were "inconclusive".

If DNA analysis were totally objective, then all 17 analysts should reach
the same conclusion. However, we found that just one agreed with the
original judgement that Robinson "cannot be excluded". Four analysts said
the evidence was inconclusive and 12 said he could be excluded. ..."

ps
What they aren't telling you about DNA profiles
and what Special Branch don't want you to know.
http://www.nutteing.chat.ru/dnapr.htm
or nutteingd in a search engine.

Valid email ***@fastmail.....fm (remove 4 of the 5 dots)
Ignore any other apparent em address used to post this message -
it is defunct due to spam.

[Paul Nutteing (valid email address in post script )]

Some more of the corruption I was not aware of
""In our experience, examination of the underlying data frequently reveals
limitations or problems that would not be apparent from the lab report,"
says William Thompson of the University of California, Berkeley, who acts as
an expert witness on DNA. However, "forensic DNA analysts tell us that they
receive requests [for DNA lab reports] from defence lawyers in only 10 to 15
per cent of cases in which their tests incriminate a suspect," Thompson
says.

Even when the defence makes a legitimate challenge, the public rarely hears
about it. In the UK, defence lawyers are granted access to DNA data on the
condition that they only use it in the case in question. If the questioned
evidence is dropped before it gets to court, this never becomes public"

The second part
http://www.newscientist.com/article/mg20727743.300-how-dna-evidence-creates-
victims-of-chance.html
probably only available, in full, for the next week


ps
What they aren't telling you about DNA profiles
and what Special Branch don't want you to know.
http://www.nutteing.chat.ru/dnapr.htm
or nutteingd in a search engine.

[GB]

Post by Paul Nutteing (valid email address in post script )
The second part
http://www.newscientist.com/article/mg20727743.300-how-dna-evidence-creates-
victims-of-chance.html
probably only available, in full, for the next week

That was a very interesting and disturbing article, which I read this
morning. It seems that DNA testing works reasonably well where there is a
good sample of DNA to test, and the sample is not contaminated in any way.
They seem to be stretching things when they get on to low copy number
testing or where two lots of DNA are combined. it does seem surprising that
this data is not more often challenged.