Concluding Thoughts

Michael D. Coble

National Institute of Standards and Technology

Probabilistic Genotyping 

Webcast (Part 1)

May 28, 2014
NIST and NIJ Disclaimer

Past and Present Funding: Interagency Agreement 

between the National Institute of Justice and NIST 

Office of Law Enforcement Standards

Points of view are mine and do not necessarily represent 

the official position or policies of the US Department of Justice or the 

National Institute of Standards and Technology. 

Certain commercial equipment, instruments, software and materials are 

identified in order to specify experimental procedures as completely 

as possible. In no case does such identification imply a 

recommendation or endorsement by the National Institute of 

Standards and Technology nor does it imply that any of the 

materials, instruments or equipment identified are necessarily the 

best available for the purpose.
Concluding Thoughts

• We need to move away from the interpretation of 

mixtures from an “allele-centric” point of view.

• Methods to incorporate probability will be 

necessary as we make this transition and confront 

issues of low-level profiles with dropout.

“Just as logic is reasoning applied to truth and falsity, 

probability is reasoning with uncertainty”

-Dennis Lindley
Concluding Thoughts

• The LR is a method to evaluate evidence that 

can overcome many of the limitations we are 

facing today.
“I didn’t think it would end this way." 

Lord of the Rings: Return of the King
“End?" 

Lord of the Rings: Return of the King
“No, the journey doesn’t end here" 

Lord of the Rings: Return of the King
“The grey rain-curtain of this world rolls 

back and all turns to silver glass.”

Lord of the Rings: Return of the King
“And then you see it...”

Lord of the Rings: Return of the King
“What Gandalf?”

“See What?”

Lord of the Rings: Return of the King
“White shores“

“And beyond...”

Lord of the Rings: Return of the King
“A far green country under a swift sunrise." 

Lord of the Rings: Return of the King
Lord of the Rings: Return of the King
“Where people use Likelihood Ratios to

interpret complex DNA mixtures." 

Lord of the Rings: Return of the King
“Well, that isn’t so bad." 

Lord of the Rings: Return of the King
“No, no it isn’t." 

Lord of the Rings: Return of the King
Concluding Thoughts

• The LR is a method to evaluate evidence that 

can overcome many of the limitations we are 

facing today.

• Probabilistic software solutions may be the way 

forward (not every mixture may be resolved!) ... 

however, we need to better understand this 

process and be able to explain the statistics as a 

community.
Interest in Probabilistic Software
Interest in Probabilistic Software
Probabilistic Genotyping – Part 2

• Will be presented sometime in September

• Planned discussions: True Allele Casework, 

DNA-View Mixture Solution, LikeLTD, Armed 

Expert, and others – depending on logistics.

• Sign up at http://www.nist.gov/forensics/nist-dnaanalyst-webinar-series-pt1.cfm for email alerts.
This Webcast

• Will be archived for at least 6 months 

(approximately 1-2 weeks from now).

• Save the date! August 6, 2014 – next webcast 

will be on Validation – new kits, new instruments.

• Give us feedback on topics for future webcasts.

– John Paul Jones - john.jones@nist.gov

– Mike Coble – mcoble@nist.gov
Acknowledgments

Contact info:

mcoble@nist.gov

+1-301-975-4330

National Institute of Justice and NIST 

OLES

Charlotte Word

Susan Berdine

Craig O’Connor

Todd Bille

Ate Kloosterman

John Paul Jones