DNA profile probabilities

when G_c=G_S then

H_p is true and =1

equation for likelihood ratio

the quantity Pr(G_c) is

the probability that a person randomly chosen from a population will have the profile type G_c

define match probability

of relevance, the probability of seeing the profile in a randomly chosen person after we have already seen that profile in a typed person, typically the suspect, Pr(G_C/G_S)

having seen a profile once,

there is an increased change we will see it again

the match probability is larger than

the profile probability

the nature of I and the value of LR

must be explained in court

if the court has a different view of I

then a scientist will need to review the interpretation of the DNA evidence

the circumstances I may define

a population group

when we say selecting a person at random we mean

choosing that person in such a way as to be as uncertain as possible about their DNA type

define a convenience sample

a set of people from whom it is easy to collect biological material in order to determine their DNA profiles, they are not a random sample, but have not been selected on the basis of their DNA profiles

a final LR value greater than 1 indicates

support for the inclusionary hypothesis

a final LR value less than 1 indicates

support for the exclusionary hypothesis

evidence

E

inclusionary evidence

H_i

exclusionary evidence

H_e

general formula for LR for comparing the probability of the evidence given two competing hypothesis is

LR is used routinely to

assess the DNA findings given multiple persons of interest together in a mixture

LR for H_p support - 1

verbal qualifier - uninformative

LR for H_p support - 2-99

verbal qualifier - limited support

LR for H_p support - 100-9,999

verbal qualifier - moderate support

LR for H_p support - 10,000-999,999

verbal qualifier - strong support

LR for H_p support - >-1,000,000

verbal qualifier - very strong support