FDC Statistical Analysis & Population Genetics 2

Question 1

A Likelihood Ratio (LR) in forensic DNA statistics compares:

Accepted Answer

The probability of the evidence given the prosecution hypothesis versus the probability of the evidence given the defense hypothesis

Answer

The LR is defined as P(evidence | prosecution hypothesis) / P(evidence | defense hypothesis), quantifying how much more likely the evidence is under one scenario compared to the other.

Question 2

When a DNA mixture is observed and the contributor number is uncertain, which statistical approach can account for all possible numbers of contributors?

Accepted Answer

Probabilistic genotyping software using continuous models

Answer

Probabilistic genotyping software using continuous models evaluates the data under all plausible contributor number hypotheses and weights them appropriately, providing more rigorous mixture statistics than binary methods.

Question 3

The Combined Probability of Inclusion (CPI) in mixture statistics represents:

Accepted Answer

The probability that a randomly selected, unrelated person could be a contributor to the mixture

Answer

CPI is the product of single-locus Probabilities of Inclusion across all tested loci, representing the overall chance that a random, unrelated individual would not be excluded as a possible contributor to the mixture.

Question 4

Which of the following best describes the 'sampling uncertainty' concern in forensic DNA statistics?

Accepted Answer

Allele frequencies estimated from finite reference databases may not perfectly represent the true population frequencies

Answer

Sampling uncertainty arises because reference population databases contain a limited number of individuals, so estimated allele frequencies carry statistical uncertainty that can be addressed using confidence intervals or conservative estimates.

Question 5

If a forensic analyst calculates an RMP of 1 in 10 quadrillion for a 20-locus CODIS profile, this statistic means:

Accepted Answer

The profile is expected to occur in approximately 1 out of every 10 quadrillion unrelated individuals

Answer

RMP expresses profile rarity — 1 in 10 quadrillion means that among unrelated individuals, we expect approximately 1 in 10^16 to share that exact profile by chance, not that guilt is established.

(FDC) Forensic DNA Certification Practice Test

(FDC) Forensic DNA Certification Practice Test

FDC Statistical Analysis & Population Genetics 2