FIGURE H-7 Accuracy index (A) values for comparison question and concealed information laboratory polygraph studies with high internal validity, by year and salience score.

NOTES: Each dataset is symbolized on the plot by the salience score that committee reviewers assigned to the study from which it was derived. Boldface type indicates concealed information studies; italic type indicates comparison question studies.

“whiskers” extend to the largest and smallest values within 1.5 times the interquartile range of the edge. Any values farther out are marked by detached dots and horizontal lines. The data in Figure H-8 suggest that studies internal to or funded by polygraph agencies do not report higher measures of polygraph validity than studies funded by other sources.

Figure H-9 shows parallel boxplots for the entire group of 52 datasets, the subgroup of 14 datasets with internal validity score better than 3, and the subgroup of four datasets with both internal validity and salience scores better than 3. Restricting to high validity and salience does not change the overall impression conveyed by these data, that characteristic values of A from laboratory studies fall in the broad range between 0.70 and 0.95, with the most characteristic values falling in or slightly above the 0.81-0.91 range, which contains half (26 of 52) of our selected datasets.

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