NAEP Technical DocumentationNumber of Items by Severity of Differential Item Functioning, Science Combined National and State Assessments, by DIF Category and Grade: 2011

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 dichotomously scored items. After reviewing "C" and "CC" items, subject area specialists decided that no items were biased, so none were deleted from the scales for this reason.

Number of dichotomously scored items, science combined national and state assessments, by differential item functioning (DIF) category and grade: 2011
Grade	DIF category	Female/Male	Black/White	Hispanic/White
NOTE: This includes all items in the assessment (the prescaling decisions). In 2011, the science assessment was conducted only at grade 8. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2011 Science Assessment.
8	C-	1	1	0
	B-	10	1	1
	A	94	102	102
	B+	1	1	3
	C+	0	1	0

Number of polytomously scored items, science combined national and state assessments, by differential item functioning (DIF) category and grade: 2011
Grade	DIF category	Female/Male	Black/White	Hispanic/White
NOTE: This includes all items in the assessment (the prescaling decisions). In 2011, the science assessment was conducted only at grade 8. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2011 Science Assessment.
8	CC-	0	0	0
	BB-	1	0	0
	AA	50	55	56
	BB+	5	1	0
	CC+	0	0	0

Items identified as 'C' items in at least one comparison, science combined national and state assessments, by block and grade: 2011
Grade	Block	Item	Scale	Comparison	Group Favored
NOTE: In 2011, the science assessment was conducted only at grade 8. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2011 Science Assessment.
8	S8	K155801	Life science	Asian/White	White
	S9	K114901	Physical science	Female/Male	Male
	S9	K114901	Physical science	Black/White	White
	S9	K156001	Physical science	Black/White	Black
	S11	K156701	Physical science	Asian/White	Asian

Last updated 06 January 2016 (GF)

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