Discriminating Power
Definition
The statistical ability of a typing system to distinguish one individual from another in a given population. Expressed as the probability that two randomly chosen individuals will have different types at the loci tested. Higher discriminating power means fewer people share the same profile.
- Measures
- Ability to distinguish individuals
- Expressed as
- Probability two random people differ
- Direction
- Higher value, fewer shared profiles
- Historical use
- Compared blood grouping to DNA typing
Common questions
Why did blood group systems have lower discriminating power than STR DNA typing?+
Blood group systems like ABO and Rh have only a handful of common phenotypes in the population, so many unrelated people share the same type, whereas STR loci have dozens of alleles each, and combining several loci multiplies the discriminating power dramatically.
Is discriminating power the same thing as a random match probability?+
They are related but not identical. Discriminating power describes the general resolving ability of a system across a population, while a random match probability is the specific statistic calculated for one profile against one reference population.
Related terms
- Antigen Degradation Rate
- The rate at which an antigen becomes undetectable on a dried stain, driven by protein denaturation, microbial protease activity, UV exposure, and...
- Antithetical Antigens
- Pairs of antigens where carrying one typically excludes the other on the same protein: C and c, E and e in the...
- Glycophorin
- A family of heavily sialylated red-cell glycoproteins. Glycophorin A carries M and N antigens; glycophorin B carries S and s antigens. Both...
- MNS System
- A blood group system comprising M and N antigens on glycophorin A (GYPA) and S and s antigens on glycophorin B (GYPB)....
- P30 (PSA)
- Prostate-specific antigen, a glycoprotein secreted by the male prostate gland and present in semen at high concentrations. ELISA or lateral-flow immunochromatographic tests...
- Precipitin Test
- A serological method in which an antiserum specific to one species' proteins is mixed with an extract of an unknown specimen. Formation...
- Random Match Probability (RMP)
- The probability that a randomly chosen unrelated person from the relevant population would match the evidence profile by chance. A very small...
- Rh System
- A blood group system defined by antigens on two proteins encoded by the RHD and RHCE genes on chromosome 1. The clinically...
- Secretor Status
- A genetic trait that determines whether a person expresses their ABO blood group antigens in secreted body fluids such as saliva, semen,...
- Short Tandem Repeat (STR)
- Short repetitive DNA sequences scattered throughout the genome, with the number of repeats varying between individuals at each locus. DNA profiling compares...
Explained in these topics
- Rh, MNS, and Other Blood Group SystemsIn forensic serology, the proportion of random pairs of individuals expected to differ at a given marker or set of markers. A marker with high discriminating p...
- The Transition from Serology to DNA Profiling in Forensic Science