NAEP Technical DocumentationResults of Differential Item Functioning (DIF) Analysis for the Reading Long-Term Trend Assessment in 2008

For dichotomously scored items, NAEP categorizes each item into one of three categories: "A" (items exhibiting no DIF), "B" (items exhibiting a weak indication of DIF), or "C" (items exhibiting a strong indication of DIF). A plus sign (+) indicates that items are differentially easier for the focal group (female, Black, or Hispanic students) than for the reference group (male or White students) after making an adjustment for the overall level of proficiency in the two groups; a minus sign (-) indicates that items are differentially more difficult for the focal group than for the reference group. For polytomously scored items, NAEP categorizes items into "AA," "BB," or "CC" categories and the plus or minus sign has the same interpretation as that for dichotomously scored items. After reviewing the only item rendering a "CC," subject area specialists determined that the item was not biased, so the item was not deleted from the scale.

Number of dichotomously scored items, reading long-term trend assessment, by differential item functioning (DIF) category and age: 2008
Age	DIF category	Female-Male	Black-White	Hispanic-White
SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2008 Reading Long-Term Trend Assessment.
9	C-	0	0	0
	B-	1	8	2
	A	81	70	78
	B+	3	6	5
	C+	0	1	0
13	C-	1	0	1
	B-	3	3	2
	A	93	78	90
	B+	2	14	5
	C+	0	3	0
17	C-	0	0	1
	B-	5	3	3
	A	86	74	81
	B+	4	15	9
	C+	0	3	1

Number of polytomously scored items, reading long-term trend assessment, by differential item functioning (DIF) category and age: 2008
Age	DIF category	Female-Male	Black-White	Hispanic-White
SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2008 Reading Long-Term Trend Assessment.
9	CC-	0	0	0
	BB-	0	1	0
	AA	3	2	3
	BB+	0	0	0
	CC+	0	0	0
13	CC-	0	0	0
	BB-	0	1	0
	AA	6	6	7
	BB+	1	0	0
	CC+	0	0	0
17	CC-	0	0	0
	BB-	0	1	0
	AA	6	6	7
	BB+	2	1	1
	CC+	0	0	0

Items identified as 'C' or 'CC' items in at least one comparison, reading long-term trend assessment, by block and age: 2008
Age	Block	Item	Category	Comparison	Group favored
SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2008 Reading Long-Term Trend Assessment.
9	R29	N028602	C	Black-White	Black
13	R21	N021201	C	Black-White	Black
	R27	N024901	C	Black-White	Black
	R27	N024902	C	Black-White	Black
	R30	N027805	C	Female-Male	Male
	R28	N026101	C	Hispanic-White	White
17	R24	N025603	C	Black-White	Black
	R27	N024902	C	Black-White	Black
	R29	N029102	C	Black-White	Black
	R22	N025502	C	Hispanic-White	White
	R24	N022101	C	Hispanic-White	Hispanic

Last updated 03 November 2011 (JL)

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