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. 2009 Aug 4;6(8):e1000121. doi: 10.1371/journal.pmed.1000121

Figure 1. Relative item information as a function of the prolonged grief attribute for 22 candidate symptoms for PGD.

Figure 1

IRT IIF analysis of 22 binary candidate symptoms for PGD was performed using a 2-PL IRM. This figure displays item information as a function of the PG attribute for all 22 of these symptoms included in this IRM, relative to the maximum information for the most informative symptom, “inability to care about others since the death.” The horizontal line in the figure represents the standard used to discriminate between 16 informative candidate symptoms retained for further analysis, and six uninformative candidate symptoms excluded from further analysis (as indicated in Table 1).