Kirsten, The W-scale of the Peabody Picture Vocabulary Test is an interval scale. This test measures a person's hearing vocabulary for Standard American English. The examiner presents the subject with a figure containing four pictures and pronounces a vocabulary word, such as "tranquil." The subject then points to the picture that best illustrates this word. The test is composed of 175 items of this sort. The manual for the test states that the W-scale has the property that all units are equal. "Thus, an increase in ability from 50 to 55 is the same amount of growth as from 100 to 105." (Dunn,L.M., & Dunn,L.M.(1981). Peabody Picture Vocabulary Test, Revised Manual for Forms L and M. Circle Pines, MN: American Guidance Service.) Arlene Vadum
