This report concludes that there is no way to know if a software defect backlog matters without further analysis, so it recommends an approach for this further analysis.
The report is available for download here: http://www.softwarevalue.com/insights/publications/ta-archives/do-software-defect-backlogs-really-matter/
To access more Trusted Advisor articles, visit: http://www.softwarevalue.com/insights/publications/#trustedadvisor