Accepting @bruce-usab's #1629 citation but not removal of the 80% bul…

…let list item.

conformance-challenges/index.html

@@ -1141,7 +1141,7 @@ <h4>Themes from Research</h4>
                             </ul>
                         </li>
                         <li>Specific success criteria for failure - 1.1.1 , 2.2., 4.1.2 (Keith et al., 2012)</li>
-			<li><q>Reliably Human Testable,</q> <q>not reliably testable</q> (Brajnick et al., 2012) average agreement was at the 70-75% mark, while the error rate was around 29%.
+			<li><q>Reliably Human Testable,</q> <q>not reliably testable</q> <a href="http://www.researchgate.net/publication/235339930_Is_accessibility_conformance_an_elusive_property_A_study_of_validity_and_reliability_of_WCAG_20">Is Accessibility Conformance an Elusive Property? (Brajnik et al. 2012)</a>, found the average agreement was at the 70-75% mark, while the error rate was around 29%.
                             <ul>
                                 <li>Expertise appears to improve (by 19%) the ability to avoid false positives. Finally, pooling the results of two independent experienced evaluators would be the best option, capturing at most 76% of the true problems and producing only 24% of false positives. Any other independent combination of audits would achieve worse results.</li>
                                 <li>This means that an 80% target for agreement, when audits are conducted without communication between evaluators, is not attainable, even with experienced evaluators.</li>