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Large-scale Assessments in Education

An IERI – International Educational Research Institute Journal

Table 6 1PL covariance matrices (DIF adjustment)

From: An item response theory approach to longitudinal analysis with application to summer setback in preschool language/literacy

Model 1

T 1

T 2

T 3

T 4

T 1

1.00

   

T 2

.71

1.66

  

T 3

.47

.59

1.91

 

T 4

.35

.46

1.30

1.66

Model 2

C 1

C 2

C 3

C 4

C 1

3.50

   

C 2

.30

1.2

  

C 3

-.35

.12

.56

 

C 4

.44

.54

.02

.98

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