Various measures of internal consistency were used in the calculation of Howarth's μ index for the state and trait scales of the State-Trait Anxiety Inventory. The results suggested that Howarth's μ is a useful index to assess state scales and to differentiate state scales from trait scales at least in the case of this inventory. Caution is urged, however, in its use with other measures which are not so well validated as this and with affective states not so well researched as anxiety.
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