ABSTRACT
Again let us begin with basic equation 1 of Chapter 2 (X = T + E) and put it in the form https://www.w3.org/1998/Math/MathML"> E = X − T . https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780203052150/a2ba952a-291f-4af7-b1a5-6acb3e41f457/content/math_85_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> In other words, the error is defined as the difference between true score and observed score. Then, if “true score” is defined, the error can be determined. True score is defined as https://www.w3.org/1998/Math/MathML"> T i = lim K → ∞ ∑ g = 1 K X i g K , https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780203052150/a2ba952a-291f-4af7-b1a5-6acb3e41f457/content/math_86_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> that is, the true score for a given person (i) is the limit that the average of his scores on a number of tests approaches, as the number of parallel tests (K) increases without limit. These tests are designated by the subscript g, which varies from 1 to K.
