Version	1.1	/	Date	of	Issue:	2.09.16 /	Issuing	Authority:	Forensic	Science	Standards	Board	(FSSB)

OSAC	RESEARCH	NEEDS	ASSESSMENT	FORM

Title	of	research	need: Probability	of	Randomly	Acquired	Characteristics

Keyword(s): RACs,	probability,	frequency,	chance	co-occurrence,	position,	shape,	geometry

Submitting	subcommittee(s): Footwear	&	Tire Date	Approved: 24-Feb-2016

(If	SAC	review	identifies	additional	subcommittees,	add	them	to	the	box	above.)

Background	Information:

1. Description	of	research	need:

Investigate	the	statistical	probabilities	of	randomly	acquired	characteristics	occurring in	the	same	position	

and	orientation	on	different	outsoles	and/or	tires.		Quantitative	results	should	include	data	originating	from	

both	high	quality	exemplars	and	crime-scene	impressions.

2. Key	bibliographic	references	relating	to	this	research	need:

Cassidy,	M.	(1995).		Footwear	Identification.		Published	by	Lightning	Powder	Company,	Inc.	in	cooperation	

with	the	Royal	Canadian	Mounted	Police.		ISBN	0-9622305-8-8,	pp.	1-176.

Stone,	R.	(2006).	Footwear	Examinations:		Mathematical	Probabilities	of	Theoretical	Individual	

Characteristics.		Journal	of	Forensic	Identification.		Vol.	56,	No.	4.		pp.		577-599.

Wilson,	H.	(2012).	Comparison	of	the	Individual	Characteristics	in	the	Outsoles	of	Thirty-Nine	Pairs	of	Adidas	

Supernova	Classic	Shoes.	Journal	of	Forensic	Identification.		Vol.	62,	No.	3,	pp.		194-203.

3a. In	what	ways	would	the	research	results	improve	current	laboratory	capabilities?

The	day-to-day	operations	of	the	laboratory	are	not	expected	to	change	as	a	function	of	this	research.		

However,	the	reporting	structure,	possible	strength	of	conclusions,	and	analyst	training	may	change	over	

time	to	incorporate	research	findings.		Downstream	digital	and	web-based	applications	for	data-analysis	(of	

crime	scene	samples)	are	also	foreseeable,	but	these would	be	long-term	outcomes	beyond	the	scope	of	

this	initiative.

3b. In	what	ways	would	the	research	results	improve	understanding	of	the	scientific	basis	for	the	

subcommittee(s)?

The	basis	of	source	identification	in	forensic	footwear	and	tire	comparison	is	a	function	of	the	perceived	

limits	in	chance	co-occurrence	of	randomly	acquired	characteristics	(RACs).		However,	the	discrimination	
Version	1.1	/	Date	of	Issue:	2.09.16 /	Issuing	Authority:	Forensic	Science	Standards	Board	(FSSB)

potential	ascribed	to	a	single	or	combination	of	RACs	is	believed	to	vary	as	a	function	of	RAC	size,	shape,	

quality,	clarity	and	complexity.		This	research	will	serve	to	evaluate	the	leading	hypothesis	and	

quantitatively	define	the	certainty	to	which	a	RAC	(or	RACs)	can	support	source	identification.

3c.		In	what	ways	would	the	research	results	improve	services	to	the	criminal	justice	system?

The	potential	for	chance	co-occurrence	of	randomly	acquired	characteristics	directly	impacts	the	degree	of	

confidence	to	which	a	conclusion	of	source	identification	can	be	made.		If	this	confidence	can	be	described	

quantitatively,	and/or	illustrated	using	research	examples,	the	trier	of	fact	will	have	additional	information	

and	illustrations	on	which	to	evaluate	the	weight	of	evidence	offered	in	criminal	proceedings	that	include	

footwear	and	tire	impression	evidence.

4.		Status	assessment	(I,	II,	III,	or	IV): I Major gap	in	

current	

knowledge

Minor	gap	in	

current	

knowledge

No	or	limited

current	research	

is	being	conducted

I III

Existing current	

research	is	being	

conducted

II IV

This	research	need	has	been	identified	by	one	or	more	subcommittees	of	OSAC	and	is	being	provided	as	an	

informational	resource	to	the	community.
Version	1.1	/	Date	of	Issue:	2.09.16 /	Issuing	Authority:	Forensic	Science	Standards	Board	(FSSB)

Approvals:

Subcommittee Approval	date: 24-Feb-2016

(Approval	is	by	majority	vote	of	subcommittee.	Once	approved,	forward	to	SAC.)

SAC

1.		Does	the	SAC	agree	with	the	research	need? Yes x No

2.		Does	the	SAC	agree	with	the	status	assessment? Yes x No

If	no,	what	is	the	status	assessment	of	the	SAC:

Approval	date: 17-Mar-2016

(Approval	is	by	majority	vote	of	SAC.		Once	approved,	forward	to	NIST	for	posting.)