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. Author manuscript; available in PMC: 2015 Sep 2.
Published in final edited form as: Assess Eff Interv. 2011 May 13;37(1):17–25. doi: 10.1177/1534508411407761

Table 3.

Screening Accuracy of Letter Clusters

Letter Cut
Points		 SE SP NPP PPP OCC
5 .27 .95 .71 .76 .72
10 .36 .93 .73 .73 .73
15 .55 .88 .79 .72 .77
20 .63 .78 .80 .60 .73
26 .90 .43 .89 .46 .60

Note. SE = Sensitivity, SP = Specificity, NPP = Negative Predictive Power, PPP = Positive Predictive Power, OCC = Overall Correct Classification.