(1)
items that many subjects asked to have explained
to them further during completion of the scale;
(2) items for which the response distribution was
severely skewed; (3) items with weak correlations
(Pearson’s correlation coefficient
,
0.40) with
the VAS for fatigue; (4) items related to other
physical symptoms, because contamination by
the other somatic symptoms should be avoided;
and (5) items whose meaning was similar to that
of another item.