ICANN should take appropriate measures to reduce the number of unreachable WHOIS registrations (as defined by the NORC Data Accuracy Study, 2009/10) by 50% within 12 months and by 50% again over the following 12 months. 

ICANN should take appropriate measures to reduce the number of undeliverable (also mentions unreliable) WHOIS registrations (as defined by the NORC Data Accuracy Study, 2009/10) by 50% within 12 months and by 50% again over the following 12 months

I think it would be abundantly clear if we used the term substantial failure in the recommendation 

ICANN should take appropriate measures to reduce the number of WHOIS registrations with a substantial failure (as defined by the NORC Data Accuracy Study, 2009/10) by 50% within 12 months and by 50% again over the following 12 months

Page 3 of the study outlines Accuracy Groups 

					Margin of error (4)
No failure	Met all three criteria fully - deliverable address, name linked to address, and registrant confirmed ownership and correctness of all details during interview	353	23,117,442	22.8%	1.4%
Minimal failure	All criteria met but minor fault noted by registrant during interview	17	1,101,176	1.1%	0.2%
	Name unable to be linked to address, but able to locate registrant and confirm ownership	312	23,024,007	22.7%	2.2%
Limited failure	Deliverable address, name linked and/or located, but unable to interview registrant to obtain confirmation.	365	24,893,476	24.6%	1.7%
Substantial failure	Undeliverable address and/or unlinkable name, however registrant located. Unable to interview registrant to obtain confirmation.	109	7,202,472	7.1%	0.9%
	Deliverable address, but unable to link or even locate the registrant, removing any chance of interview.	177	13,949,721	13.8%	2.2%
Full failure	Failed on all criteria - undeliverable address and unlinkable, missing, or patently false name, unable to locate to interview

Susan Kawaguchi