definitions (per SWGDAM & QAS)

Question 1

accreditation

Answer 1

the formal recognition that a laboratory meets or exceeds a list of standards, including the FBI’s QAS, to perform specific tests
accreditation is administered by a nonprofit professional association of persons actively involved in forensic science that is nationally recognized within the forensic science community in accordance with the provisions of the Federal DNA Identification Act or subsequent laws

Question 2

allele

Answer 2

a form of a gene that is located at a specific location on a specific chromosome alleles targeted in STR analysis vary in length

Question 3

analytical threshold

Answer 3

the minimum height requirement at and above which detected peaks can be reliably distinguished from background noise
peaks above this threshold are generally not considered noise and are either artifacts or true alleles

Question 4

artifact

Answer 4

a non-allelic product of the amplification process (e.g., stutter, non-templated nucleotide addition, or other non-specific product), an anomaly of the detection process (e.g., pull-up or spike), or a by-product of primer synthesis (e.g., “dye blob”)

Question 5

assumed contributor

Answer 5

an individual whose DNA on an item of evidence is reasonably expected

Question 6

binary model/method

Answer 6

an interpretation scheme in which there are only two values (possible or not possible) for each decision (e.g., a peak is either “an allele” or “not an allele”; a genotype is “included” or “not included”)

Question 7

composite profile

Answer 7

a DNA profile generated by combining typing results from different loci obtained from multiple injections of the same amplified sample and/or multiple amplifications of the same DNA extract
when separate extracts from different locations on a given evidentiary item are combined prior to amplification, the resultant DNA profile is not considered a composite profile

Question 8

deduced profile

Answer 8

inference of an unknown contributor’s DNA profile after taking into consideration the contribution of a known/assumed contributor’s DNA profile based on quantitative peak height information

Question 9

distinguishable mixture

Answer 9

a DNA mixture in which relative peak height ratios allow deconvolution of the profiles of major/minor contributor(s)

Question 10

dropout

Answer 10

when one or more alleles present in a sample are not observed above the analytical threshold

Question 11

evidence/questioned sample

Answer 11

biological sample recovered from a crime scene or collected from persons or objects associated with a crime

Question 12

exclusion

Answer 12

a conclusion that eliminates an individual as a potential contributor of DNA obtained from an evidentiary item based on the comparison of known and questioned DNA profiles (or multiple questioned DNA profiles to each other)

Question 13

exclusionary hypothesis

Answer 13

also referred to as Hd or H2; the term typically used in the denominator of the likelihood ratio to represent the defense hypothesis, which does not include the person of interest as a contributor to the DNA profile

Question 14

genotype

Answer 14

results of autosomal STR analysis of an individual at one or more genetic loci

Question 15

guidelines

Answer 15

a set of general principles used to provide directions and parameters for decision making

Question 16

heterozygote

Answer 16

an individual having different alleles at a particular locus; usually manifested as two distinct peaks for a locus in an electropherogram

Question 17

homozygote

Answer 17

an individual having the same (or indistinguishable) alleles at a particular locus; manifested as a single peak for a locus in an electropherogram

Question 18

inclusion

Answer 18

a conclusion for which an individual cannot be excluded as a potential contributor of
DNA obtained from an evidentiary item based on the comparison of known and questioned DNA profiles (or multiple questioned DNA profiles to each other)

Question 19

inclusionary hypothesis

Answer 19

also referred to as Hp or H1; the term typically used in the numerator of the likelihood ratio to represent the prosecution hypothesis, which includes the person of interest as a contributor to the DNA profile

Question 20

inconclusive

Answer 20

a determination that no conclusion (i.e., inclusion/exclusion) can be drawn from the comparison of a reference sample to suitable data
this could also result from statistical analyses that fail to provide sufficient support for
an inclusion or exclusion

Question 21

indistinguishable mixture

Answer 21

a DNA mixture in which relative peak height ratios are insufficient to attribute alleles to individual contributor(s)

Question 22

intimate sample

Answer 22

a biological sample from an evidence item that is obtained directly from an individual’s body; it is not unexpected to detect that individual’s allele(s) in the DNA typing results

Question 23

known sample

Answer 23

biological material for which the identity of the donor is established and used for comparison purposes

Question 24

likelihood ratio (LR)

Answer 24

the ratio of two probabilities of the same event under different and mutually exclusive hypotheses
typically the numerator contains the prosecution’s hypothesis and the denominator the defense’s hypothesis

Question 25

locus

Answer 25

the specific physical location of a gene on a chromosome in forensic DNA analysis, it refers to the specific sites being tested

Question 26

major contributor(s)

Answer 26

an individual(s) who can account for the predominance of the DNA in a mixed profile

Question 27

masked allele

Answer 27

an allele of the minor contributor that may not be readily distinguishable from the alleles of the major contributor or an artifact

Question 28

minor contributor(s)

Answer 28

an individual(s) who can account for the lesser portion of the DNA in a mixed profile

Question 29

mixture

Answer 29

a DNA typing result originating from two or more individuals

Question 30

mixture ratio

Answer 30

the relative proportion of the DNA contributions of multiple individuals to a mixed DNA typing result, as determined by the use of quantitative peak height information when expressed as a percentage it is termed a mixture proportion

Question 31

noise

Answer 31

background signal detected by a data collection instrument

Question 32

partial profile

Answer 32

a DNA profile for which complete typing results are not obtained at all tested loci due, for example, to DNA degradation, inhibition of amplification and/or low-quantity template

Question 33

peak height ratio (PHR)

Answer 33

the relative proportion of two alleles at a given locus, as determined by dividing the peak height of an allele with a lower relative fluorescence unit (RFU) value by the peak height of an allele with a higher RFU value, and then multiplying this value by 100 to express the PHR as a percentage used as an indication of which alleles may be heterozygous pairs and also in mixture deconvolution

Question 34

probabilistic genotyping

Answer 34

the use of biological modeling, statistical theory, computer algorithms, and probability distributions to calculate likelihood ratios (LRs) and/or infer genotypes for the DNA typing results of forensic samples

Question 35

random match probability (RMP)

Answer 35

the probability of randomly selecting an unrelated individual from the population who could be a potential contributor to an evidentiary profile

Question 36

restricted

Answer 36

referring to a statistical approach conditioned on the number of contributors and with consideration of quantitative peak height information and inference of contributor mixture ratios used to limit the genotypic combinations of possible contributors

Question 37

single-source profile

Answer 37

DNA typing results determined to originate from one individual based on peak height ratio assessments and the number of alleles at given loci

Question 38

source attribution

Answer 38

a declaration which identifies an individual as the source of the DNA that produced an evidentiary single-source or deduced contributor profile this statement is based on a statistical estimate that meets or exceeds a laboratory defined threshold

Question 39

stochastic effects

Answer 39

the observation of intra-locus peak imbalance and/or allele drop-out resulting from random, disproportionate amplification of alleles in low-quantity template samples

Question 40

stochastic threshold

Answer 40

the peak height value below which it is reasonable to assume that, at a given locus, allelic dropout of a sister allele in a heterozygous pair may have occurred

Question 41

stutter

Answer 41

a minor peak typically observed one repeat unit smaller than a primary STR allele resulting from strand slippage during amplification

Question 42

theta (θ)

Answer 42

a value used to adjust statistical calculations that rely on population databases to correct for substructure within populations

Question 43

uninterpretable

Answer 43

the determination that DNA results at one or more loci cannot be interpreted due to poor or limited data quality

Question 44

unrestricted

Answer 44

referring to a statistical approach performed without consideration of quantitative peak height information and inference of contributor mixture ratios

Question 45

accuracy

Answer 45

the ability of a measurement to give results close to a true value

Question 46

administrative review

Answer 46

an evaluation of the report and supporting documentation for consistency with laboratory policies and for editorial correctness

Question 47

analyst

Answer 47

an employee or contract employee, that has successfully completed the laboratory’s training requirements for casework sample analysis, passed a competency test, and has entered into a proficiency testing program according to these standards this individual can conduct and/or direct the analysis of forensic samples, interpret data, reach conclusions, and generate reports

Question 48

analytical control

Answer 48

a sample used to demonstrate that a method works correctly and to ensure the data are valid

Question 49

analytical documentation

Answer 49

the documentation of procedural notes, controls, and instruments used; observations made; results of tests performed; and charts, graphs, photos, and other documentation generated which are used to support the analyst’s conclusions

Question 50

analytical procedure

Answer 50

an orderly, step-by-step process designed to ensure operational uniformity and to minimize analytical drift

Question 51

annual

Answer 51

once per calendar year

Question 52

audit

Answer 52

an on-site inspection used to evaluate, confirm, and/or determine the extent to which specified requirements are fulfilled

Question 53

audit team

Answer 53

one or more individuals, including at least one auditor, that performs an inspection of a laboratory at least one audit team member shall be or have been an analyst previously qualified in the laboratory’s current DNA technologies and platforms

Question 54

auditor

Answer 54

an individual who has successfully completed the FBI’s DNA auditor training course

Question 55

biochemistry

Answer 55

the study of the nature of biologically important molecules in living systems, DNA replication and protein synthesis, and the quantitative and qualitative aspects of cellular metabolism

Question 56

casework reference sample

Answer 56

biological material (e.g., buccal swab, fingerprick, or blood draw) obtained directly from a known individual and used for purposes of comparison to forensic samples

Question 57

certified reference material

Answer 57

material for which values are obtained by a technically valid procedure and accompanied by, or traceable to, a certificate or other documentation which is issued by a certifying body (e.g., NIST)

Question 58

CODIS

Answer 58

Combined DNA Index System administered by the FBI CODIS links DNA evidence obtained from crime scenes, thereby identifying serial criminals compares crime scene evidence to DNA profiles from offenders, thereby providing investigators with the identity of the putative perpetrator contains profiles from missing persons, unidentified human remains, and relatives of missing persons there are three levels of CODIS: the Local DNA Index System (LDIS), used by individual laboratories; the State DNA Index System (SDIS), used at the state level to serve as a state’s DNA database containing DNA profiles from LDIS laboratories; and the National DNA Index System (NDIS), managed by the FBI as the nation’s DNA database containing all DNA profiles uploaded by participating states

Question 59

CODIS user

Answer 59

an employee or contract employee who has login access to the CODIS (i.e., State or Local) system and is authorized to read, add, modify and/or delete DNA records in CODIS

Question 60

competency testing

Answer 60

a test or series of tests (practical, written, and/or oral) designed to establish that an individual has demonstrated achievement of technical skills and met minimum standards of knowledge necessary to perform forensic DNA analysis

Question 61

competency

Answer 61

the demonstration of technical skills and knowledge necessary to perform forensic DNA analysis successfully

Question 62

contamination

Answer 62

the unintentional introduction of exogenous DNA into a sample or analytical control during DNA testing

Question 63

continuing education

Answer 63

an educational activity (such as a class, lecture series, conference, seminar, or short course) that is offered by a recognized organization or individual that brings participants up-to-date in their relevant area of knowledge

Question 64

corrective action plan

Answer 64

evaluates and remediates a nonconformity with the goal to identify, correct, and/or prevent reoccurrence of the nonconformity, when possible

Question 65

critical equipment/instruments

Answer 65

those equipment/instruments whose accurate functionality directly affects the results of the analysis and requires calibration, certification, or performance check prior to use and periodically thereafter

Question 66

critical reagents

Answer 66

those whose performance is vital to the success of the DNA testing and require testing on known samples before use on forensic or casework reference samples

Question 67

disposition of evidence

Answer 67

the documentation of the retention, return, or consumption of the evidence item(s) upon completion of DNA testing

Question 68

DNA record

Question 69

electrophoresis detection system

Answer 69

a platform that allows for the size separation of DNA molecules through a fluid or a gel under the influence of an electric field and the subsequent detection of the separated molecules by fluorescence or other means

Question 70

evidence

Answer 70

an item submitted for DNA testing and/or a derivative of an item as defined by the laboratory that is subject to a chain of custody

Question 71

expert system

Answer 71

a software program or set of software programs designed to interpret single source DNA data in accordance with laboratory defined quality assurance rules and identify DNA data not satisfying laboratory defined quality assurance rules, without human intervention

Question 72

forensic DNA analysis

Answer 72

(also referred to as Forensic DNA testing) is the process of isolation, detection, identification, and evaluation of biological evidence in criminal matters using DNA technologies

Question 73

forensic sample

Answer 73

a biological sample originating from and associated with evidence from a crime scene a sample associated with evidence from a crime scene may include a sample that has been carried away from the crime scene

Question 74

functional testing

Answer 74

a process to confirm that a software performs the tasks as expected

Question 75

genetics

Answer 75

the study of inherited traits, genotype/phenotype relationships, and population/species differences in allele and genotype frequencies

Question 76

guidelines

Answer 76

a set of general principles used to provide direction and parameters for decision making

Question 77

interpretation software

Answer 77

a tool to assist the analyst in assessing the analyzed data by applying quality assurance rules, performing mixture deconvolution, and/or evaluating comparisons interpretation software may include probabilistic genotyping software or expert systems

Question 78

known samples

Answer 78

biological material whose identity or DNA type is established

Question 79

laboratory

Answer 79

a facility: 1. employing at least two full-time employees who are qualified analysts 2. having and maintaining the capability to perform the DNA analysis of forensic samples and/or casework reference samples at that facility

Question 80

laboratory support personnel

Answer 80

employees or contract employees who perform laboratory support duties exclusive of analytical procedures on forensic or casework reference samples

Question 81

module

Answer 81

an independent but interrelated part of software that performs a distinct function

Question 82

molecular biology

Answer 82

the study of the theories, methods, and techniques used in the study and analysis of gene structure, organization, and function

Question 83

negative amplification control

Answer 83

an analytical control that is used to detect DNA contamination of the amplification reagents this analytical control consists of only amplification reagents without the intentional addition of template DNA

Question 84

NIST

Answer 84

National Institute of Standards and Technology

Question 85

nonconformity

Answer 85

not meeting, implementing, maintaining, or complying with one or more of the requirements of these standards or a laboratory’s procedures, policies, or other quality system documents

Question 86

outsourcing

Answer 86

the utilization of a vendor laboratory to provide DNA services in which the NDIS participating laboratory takes or retains ownership of the DNA data outsourcing does not require the existence of a contractual agreement or the exchange of funds

Question 87

performance check

Answer 87

a quality assurance measure to assess the functionality of laboratory critical equipment and instruments

Question 88

policy

Answer 88

an organization’s high level plan for a course of action or to address a requirement

Question 89

polymerase chain reaction (PCR)

Answer 89

an enzymatic process by which a specific region of DNA is replicated during repetitive cycles, which consist of the following: 1. denaturation of the template 2. annealing of primers to complementary sequences at an empirically determined temperature 3. extension of the bound primers by a DNA polymerase

Question 90

positive amplification control

Answer 90

an analytical control that is used to determine if the PCR performed properly this control consists of the amplification reagents and a known DNA sample

Question 91

precision

Answer 91

characterizes the degree of mutual agreement among a series of individual measurements, values, and/or results

Question 92

preferential amplification

Answer 92

the unequal amplification of the two alleles present in a heterozygous locus during the polymerase chain reaction

Question 93

procedure

Answer 93

(protocol, standard operating procedure, or other equivalent) is a series of instructions to be followed in performing a specified task or under specific circumstances

Question 94

proficiency testing

Answer 94

a quality assurance measure used to monitor performance and identify areas in which improvement may be needed proficiency tests may be classified as: 1. an internal proficiency test, which is produced by the agency undergoing the test 2. an external proficiency test, which is a test obtained from a proficiency test provider accredited to the current applicable standard of the International Organization for Standardization and the applicable test is included on the proficiency test provider’s scope of accreditation

Question 95

qualified

Answer 95

an adjective used to describe an individual who meets the requirements for the position, has successfully completed the laboratory’s applicable training requirements, and is authorized to perform a specific task or role

Question 96

quantitative PCR (qPCR)

Answer 96

RT PCR - a method of determining the concentration of DNA in a sample by use of the polymerase chain reaction

Question 97

reagent

Answer 97

a substance or mixture of substances used in the analysis process to detect, measure, produce, or interact with other substances

Question 98

reagent blank control

Answer 98

an analytical control that is used to monitor contamination from extraction to DNA typing results and contains no intentionally added template DNA

Question 99

review

Answer 99

an evaluation of documentation to check for consistency, accuracy, completeness, and compliance

Question 100

semi-annual

Answer 100

used to describe an event that takes place two times during one calendar year, with the first event taking place in the first six months of that year and the second event taking place in the second six months of that year, and where the interval between the two events is at least four months and not more than eight months

Question 101

sensitivity studies

Answer 101

are used to assess the ability to obtain reliable results from a range of DNA quantities, to include the upper and lower limits of the assay also used to assess the ability of the system to reliably determine the presence of a contributor’s DNA over a broad variety of evidentiary typing results (to include mixtures and low-level DNA quantities)

Question 102

specificity studies

Answer 102

used to evaluate the ability of the system to provide reliable results over a broad variety of evidentiary typing results (to include mixtures and low-level DNA quantities)

Question 103

stochastic threshold

Answer 103

the peak height or signal magnitude value, determined through validation studies, below which it is reasonable to assume that, at a given locus, allelic dropout of a sister allele in a heterozygous pair may have occurred

Question 104

technical leader

Answer 104

an employee who is accountable for the technical operations of the laboratory and who is authorized to initiate, suspend, and resume laboratory operations

Question 105

technical review

Answer 105

an evaluation of reports, notes, data, and other documents to ensure there is an appropriate and sufficient basis for the scientific conclusions

Question 106

technical reviewer

Answer 106

an employee or contract employee who is a current or previously qualified analyst that performs a technical review of, and is not an author of, the applicable report or its contents

Question 107

technician

Answer 107

an employee or contract employee who performs analytical procedures on forensic samples or casework reference samples under the direction of a qualified analyst technicians do not interpret data to reach conclusions on typing results or prepare final reports

Question 108

test kit

Answer 108

a preassembled set of reagents (or laboratory assembled equivalent) that allows the user to conduct a specific DNA extraction, quantification, or amplification method a laboratory assembled equivalent may be referred to as a test system

Question 109

typing test kit

Answer 109

a preassembled set of reagents (or laboratory assembled equivalent) that is used to generate a DNA type

Question 110

uninterpretable

Answer 110

a determination that DNA data cannot be interpreted (e.g., due to poor or limited data quality, data that fail to meet laboratory quality requirements) uninterpretable data may result in an inconclusive conclusion

Question 111

validation

Answer 111

a process by which a method is evaluated to determine its efficacy and reliability for forensic casework analysis and includes the following: 1. developmental validation, which is the acquisition of test data and determination of conditions and limitations of a new or novel DNA method for use on forensic samples 2. internal validation, which is an accumulation of test data within the laboratory to demonstrate that established methods and procedures perform as expected in the laboratory

Question 112

work product

Answer 112

the material that is generated as a function of analysis that is not subject to a chain of custody