NAEP Technical Documentation

Number of Items by Severity of Differential Item Functioning in the Science Combined National and State Assessment: 2015

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

Number of dichotomously scored items, science combined national and state assessment, by differential item functioning (DIF) group, grade, and DIF category: 2015

Grade	DIF category	Female/Male	Black/White	Hispanic/White
4	C-	1	0	0
	B-	3	5	3
	A	113	112	115
	B+	0	1	0
	C+	1	0	0
8	C-	3	1	0
	B-	6	1	1
	A	113	116	118
	B+	0	2	3
	C+	0	2	0
12	C-	7	0	0
	B-	4	5	4
	A	119	119	126
	B+	2	7	2
	C+	0	1	0
NOTE: This includes all items in the assessment (the prescaling decisions). SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2015 Science Assessment.

Number of polytomously scored items, science combined national and state assessment, by differential item functioning (DIF) group, grade, and DIF category: 2015

Grade	DIF category	Female/Male	Black/White	Hispanic/White
4	CC-	0	0	0
	BB-	0	0	0
	AA	47	48	47
	BB+	1	0	1
	CC+	0	0	0
8	CC-	0	0	0
	BB-	1	1	0
	AA	49	53	54
	BB+	5	1	1
	CC+	0	0	0
12	CC-	1	3	1
	BB-	1	2	1
	AA	65	59	59
	BB+	0	3	5
	CC+	0	0	1
NOTE: This includes all items in the assessment (the prescaling decisions). SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2015 Science Assessment.

Items identified as "C" items in at least one comparison, science combined national and state assessment, by grade and block: 2015

Grade	Block	Item	Subscale	Comparison	Group Favored
4	S8	K078601	Life science	Female/Male	Female
	S11	K165301	Earth and space sciences	Female/Male	Male
8	S5	K121403	Physical science	Female/Male	Male
	S9	K114901	Physical science	Black/White; Female/Male	White; Male
	S9	K156001	Physical science	Black/White	Black
	S9	K156002	Physical science	Black/White	Black
	S9	K111401	Earth and space sciences	Female/Male	Male
12	S6	K142801	Physical science	Female/Male	Male
	S6	K158101	Life science	Female/Male	Male
	S7	K141901	Earth and space sciences	Female/Male	Male
	S8	K137103	Physical science	Female/Male	Male
	S9	K175501	Earth and space sciences	Female/Male	Male
	S10	K174501	Physical science	Female/Male	Male
	S11	K139301	Earth and space sciences	Female/Male	Male
	S12	K127401	Life science	Black/White	Black
SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2015 Science Assessment.

Items identified as "CC" items in at least one comparison, science national assessment, by grade and block: 2015

Grade	Block	Item	Subscale	Comparison	Group Favored
12	S3	K139001	Life science	Black/White; White/Hispanic	White
	S8	K142401	Earth and space sciences	Black/White; Female/Male	White; Male
	S9	K173301	Physical science	Black/White	White
	S12	K130001	Physical science	Hispanic/White	Hispanic
SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2015 Science Assessment.

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