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NAEP Analysis and Scaling → Estimation of NAEP Score Scales → Treatment of Items in NAEP to Avoid Violations of Assumptions → Results of NAEP DIF Analyses → Results of NAEP DIF Analyses for the Science National Main Assessment in 2000 (Accommodations Permitted [R3])

NAEP Technical DocumentationResults of NAEP DIF Analyses for the Science National Main Assessment in 2000 (Accommodations Permitted [R3])

For dichotomously scored items, NAEP categorizes each item into one of three categories:

• "A" (items exhibiting no DIF),

• "B" (items exhibiting a week 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 by grade and severity of differential item functioning, science national main assessment (accommodations permitted [R3]): 2000

Grade	DIF category	Analysis
		Male/female	White/Black	White/Hispanic
4	C-	1	0	0
	B-	2	2	1
	A	31	30	31
	B+	0	2	2
	C+	0	0	0
8	C-	1	1	0
	B-	4	1	2
	A	35	36	38
	B+	2	4	2
	C+	0	0	0
12	C-	3	0	1
	B-	4	2	4
	A	34	36	35
	B+	0	3	1
	C+	0	0	0
SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2000 Science Assessment.

Number of polytomously scored items by grade and severity of differential item functioning, science national main assessment (accommodations permitted [R3]): 2000

Grade	DIF category	Analysis
		Male/female	White/Black	White/Hispanic
4	CC-	0	1	0
	BB-	1	0	1
	AA	9	8	9
	BB+	0	1	0
	CC+	0	0	0
8	CC-	0	0	0
	BB-	2	0	0
	AA	15	17	17
	BB+	1	0	0
	CC+	0	1	1
12	CC-	0	0	1
	BB-	1	2	1
	AA	16	16	15
	BB+	1	0	1
	CC+	0	0	0
SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2000 Science Assessment.

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