Similarities

  • The relationship of derived scores is the same, e.g.,

    • High correlation, (0.95) of number right scores and scale scores

    • Scale score has the same percentile rank for both methods

Differences

  • Methods of deriving scores

  • The number of scale scores possible

    • Number right = limited to the number of items

    • IRT = unlimited or is limited by the scale (ex. 100-500)