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SOUTH AFRICAN QUALIFICATIONS AUTHORITY 
REGISTERED UNIT STANDARD THAT HAS PASSED THE END DATE: 

Interpret DNA results from a statistical perspective 
SAQA US ID UNIT STANDARD TITLE
243252  Interpret DNA results from a statistical perspective 
ORIGINATOR
SGB Forensic Science 
PRIMARY OR DELEGATED QUALITY ASSURANCE FUNCTIONARY
-  
FIELD SUBFIELD
Field 08 - Law, Military Science and Security Safety in Society 
ABET BAND UNIT STANDARD TYPE PRE-2009 NQF LEVEL NQF LEVEL CREDITS
Undefined  Regular  Level 6  Level TBA: Pre-2009 was L6  10 
REGISTRATION STATUS REGISTRATION START DATE REGISTRATION END DATE SAQA DECISION NUMBER
Passed the End Date -
Status was "Reregistered" 		 2018-07-01  2023-06-30  SAQA 06120/18 
LAST DATE FOR ENROLMENT LAST DATE FOR ACHIEVEMENT
2026-06-30   2029-06-30  

In all of the tables in this document, both the pre-2009 NQF Level and the NQF Level is shown. In the text (purpose statements, qualification rules, etc), any references to NQF Levels are to the pre-2009 levels unless specifically stated otherwise.  

This unit standard does not replace any other unit standard and is not replaced by any other unit standard. 

PURPOSE OF THE UNIT STANDARD 
This unit standard will enable learners to perform the statistical interpretation of DNA (De-oxyiribonucleic acid) results. These results may be used in forensic examinations and possible future judicial processes. Learners credited with this unit standard will possess detailed knowledge regarding the principles of and international requirements when applying statistics on forensic DNA profiles and DNA databases.

A learner acquiring this unit standard will have skills, knowledge and experience to:
  • Explain underlying principles of population genetics in forensic examinations.
  • Demonstrate knowledge of concepts in population databases.
  • Calculate match probability of DNA profiles in paternity casework.
  • Justify DNA statistical findings. 
    		•

    LEARNING ASSUMED TO BE IN PLACE AND RECOGNITION OF PRIOR LEARNING 
  • Mathematics on NQF level 5. 
    		•

    UNIT STANDARD RANGE 
    A given situation refers to but is not limited to structured scenarios, actual scenarios, case studies and mock trials. 

    Specific Outcomes and Assessment Criteria: 

    SPECIFIC OUTCOME 1 
    Explain underlying principles of population genetics in forensic examinations. 

    ASSESSMENT CRITERIA     

    ASSESSMENT CRITERION 1 
    Principles underlying population genetics is explained using examples. 
    ASSESSMENT CRITERION RANGE 
    Principles include reference to probability theory.
     

    ASSESSMENT CRITERION 2 
    Laws of probability are explained using examples. 

    ASSESSMENT CRITERION 3 
    Principles underlying the application of statistics are explained in order to determine the statistical value of DNA profiles. 
    ASSESSMENT CRITERION RANGE 
    Principles may include but are not limited to: ideal population; the Hardy Weinberg equilibrium principle (including explaining the formulas for homozygous and heterozygous loci), match probability, upper and lower match probability (including examples of upper and lower match probability; and providing an complete example illustrating the calculation method for a match probability for a single stain and mixture), convenience sampling, population database, "odds ration" the odds form of the Bayes' theorem.
     

    ASSESSMENT CRITERION 4 
    Power of discrimination on a set of DNA loci is calculated in order to establish the value of DNA profiling in the judicial process. 

    ASSESSMENT CRITERION 5 
    DNA profiling and fingerprint examination are assessed in order to compare the uniqueness of the test methods. 

    SPECIFIC OUTCOME 2 
    Demonstrate knowledge of concepts in population databases. 

    ASSESSMENT CRITERIA     

    ASSESSMENT CRITERION 1 
    Principles underlying DNA match probability are explained in order to present a statistical finding. 
    ASSESSMENT CRITERION RANGE 
    Principles do not refer to the use of a (population) database.
     

    ASSESSMENT CRITERION 2 
    The validity of the NDSD (National DNA Statistics Database) is assessed for use in forensic examinations. 
    ASSESSMENT CRITERION RANGE 
    Assessment includes relating to the current size and representativeness of the NDSD.
     

    ASSESSMENT CRITERION 3 
    The influence of population substructure on match probability calculations is explained in order to determine variance of identity. 

    ASSESSMENT CRITERION 4 
    The significance of difference between population groups is evaluated using allele frequencies. 

    SPECIFIC OUTCOME 3 
    Calculate match probability of DNA profiles in paternity casework. 
    OUTCOME RANGE 
    At least three following three match probabilities must be calculated:
  • A set trio case
  • A scenario where one of the parents is absent
  • Calculation of the paternity whereby the relation of the alleged father is specified 
    		•

    ASSESSMENT CRITERIA     

    ASSESSMENT CRITERION 1 
    The formula of a paternity index is deduced from Bayes theorem in order to calculate a match probability. 

    ASSESSMENT CRITERION 2 
    Calculating paternity, maternity and parentage is performed in case scenarios to establish relatedness. 

    ASSESSMENT CRITERION 3 
    Principles underlying match probability of DNA profiles are explained using examples. 
    ASSESSMENT CRITERION RANGE 
    Principles refer to the mathematical and genetic principles used when conducting calculations to determine paternity exclusion and missing persons.
     

    ASSESSMENT CRITERION 4 
    The strength of paternity calculations used in a given situation is explained to justify the validity of results. 

    SPECIFIC OUTCOME 4 
    Justify DNA statistical findings. 

    ASSESSMENT CRITERIA     

    ASSESSMENT CRITERION 1 
    The different ways of expressing statistical findings are explained in order to determine individuality. 
    ASSESSMENT CRITERION RANGE 
    This includes expressing statistical findings in the form of a match probability or likelihood ratio.
     

    ASSESSMENT CRITERION 2 
    The possible incorrect interpretation of statistical findings in the judicial process is explained with examples. 
    ASSESSMENT CRITERION RANGE 
    Possible incorrect interpretation of statistical findings refers to the prosecutor's fallacy (transposed conditional) and defendant's fallacy.
     

    ASSESSMENT CRITERION 3 
    Cross-examination of DNA statistical findings is assessed in a given situation. 

    ASSESSMENT CRITERION 4 
    International and national recommendations concerning the interpretation of statistical findings are evaluated in terms of their influence on the use of statistical findings. 


    UNIT STANDARD ACCREDITATION AND MODERATION OPTIONS 
  • Anyone assessing a learner against this unit standard must be registered as an assessor with the relevant ETQA.
  • Any institution offering learning that will enable achievement of this unit standard must be accredited as a provider through the relevant ETQA.
  • Moderation of assessment will be overseen by the relevant ETQA according to the moderation guidelines in the relevant qualification and the agreed ETQA procedures.

    Assessor must be competent in the outcomes of this unit standard. 
    		•

    UNIT STANDARD ESSENTIAL EMBEDDED KNOWLEDGE 
  • Quality management.
  • The use of population genetics in forensic examinations.
  • Judicial procedure pertaining to forensic evidence.
  • Evidential value.
  • Concepts: probability, statistics and genetics.
  • Calculations: for random match probability estimates and likelihood ratios.
  • Approaches: interpreting mixtures and results from degraded DNA profiles including probabilities of exclusion.
  • Kinship analysis and paternity relatedness analysis.
  • National Research Council US report on the "The evaluation of Forensic DNA Evidence" published in 1996 (NRCII:1996).
  • DNA Advisory Board recommendation on statistics published in the July 2000 issue of Forensic Science Communications.
  • South African National Accreditation System standard for DNA testing laboratories.
  • Estimating:

    > Random-match probabilities for population structure.
    > Random-match probabilities for persons from the same sub-population.
    > Random-match probabilities persons where no adequate reference (population) database exists.
    > Random-match probabilities regarding relatives.
    > Random-match probabilities regarding the results of a database search.
  • The concept of ceiling and interim ceiling principle.
  • The concept of incorporating a laboratory error rate in match probability calculations. 
    		•

    UNIT STANDARD DEVELOPMENTAL OUTCOME 
    N/A 

    UNIT STANDARD LINKAGES 
    N/A 


    Critical Cross-field Outcomes (CCFO): 

    UNIT STANDARD CCFO IDENTIFYING 
    Utilise appropriate standard operating procedures in the field of the Statistical Interpretation of DNA results in a case to achieve desired outcomes, in line with international accepted forensic practice. 

    UNIT STANDARD CCFO WORKING 
    Work effectively with others as members of a team within the process of DNA analysis. 

    UNIT STANDARD CCFO ORGANISING 
    Organise oneself and one's activities so that all requirements are met in achieving competence in the Statistical Interpretation of DNA results in a case. 

    UNIT STANDARD CCFO COMMUNICATING 
    Communicate effectively with others within the process of DNA analysis, as well as external role-players in order to achieve the aims of documentation, report writing and expert witness testimony utilizing the modes of oral and written communication. 

    UNIT STANDARD ASSESSOR CRITERIA 
    N/A 

    REREGISTRATION HISTORY 
    As per the SAQA Board decision/s at that time, this unit standard was Reregistered in 2012; 2015. 

    UNIT STANDARD NOTES 
    N/A 

    QUALIFICATIONS UTILISING THIS UNIT STANDARD: 
      ID QUALIFICATION TITLE PRE-2009 NQF LEVEL NQF LEVEL STATUS END DATE PRIMARY OR DELEGATED QA FUNCTIONARY
    Elective  57977   National Certificate: Forensic Biology  Level 6  Level TBA: Pre-2009 was L6  Passed the End Date -
    Status was "Reregistered"     		 2023-06-30  SAS SETA 


    PROVIDERS CURRENTLY ACCREDITED TO OFFER THIS UNIT STANDARD: 
    This information shows the current accreditations (i.e. those not past their accreditation end dates), and is the most complete record available to SAQA as of today. Some Primary or Delegated Quality Assurance Functionaries have a lag in their recording systems for provider accreditation, in turn leading to a lag in notifying SAQA of all the providers that they have accredited to offer qualifications and unit standards, as well as any extensions to accreditation end dates. The relevant Primary or Delegated Quality Assurance Functionary should be notified if a record appears to be missing from here.
     
    NONE 


    All qualifications and part qualifications registered on the National Qualifications Framework are public property. Thus the only payment that can be made for them is for service and reproduction. It is illegal to sell this material for profit. If the material is reproduced or quoted, the South African Qualifications Authority (SAQA) should be acknowledged as the source.