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NAEP Analysis and Scaling → Estimation of NAEP Score Scales → Treatment of Items to Avoid Violations of Assumptions → Results of NAEP Differential Item Functioning Analyses → Results of NAEP Differential Item Functioning Analyses for the Science Assessment in 2005

NAEP Technical DocumentationResults of NAEP Differential Item Functioning Analyses for the Science Assessment in 2005

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 by grade and differential item functioning (DIF) category, science combined national and state main assessment: 2005

Grade	DIF category	Female-male	Black-White	Hispanic-White
4	C-	1	0	0
	B-	3	2	2
	A	106	110	108
	B+	2	0	2
	C+	0	0	0
8	C-	1	0	2
	B-	10	7	4
	A	141	148	148
	B+	3	1	2
	C+	1	0	0
12	C-	6	0	0
	B-	15	9	6
	A	116	122	132
	B+	6	13	6
	C+	1	0	0
SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2005 Science Assessment.

Number of polytomously scored items by grade and differential item functioning (DIF) category, science combined national and state main assessment: 2005

Grade	DIF category	Female-male	Black-White	Hispanic-White
4	CC-	0	0	0
	BB-	1	0	2
	AA	38	40	38
	BB+	1	0	0
	CC+	0	0	0
8	CC-	1	0
	BB-	3	2	2
	AA	57	64	64
	BB+	5	0	1
	CC+	1	1	0
12	CC-	1	1	3
	BB-	3	3	4
	AA	44	50	52
	BB+	9	3	0
	CC+	2	2	0
SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2005 Science Assessment.

Items identified as 'C' or 'CC' items in at least one comparison, by grade and block, science combined national and state main assessment: 2005

Grade	Block	Item	Scale	Category	Comparison	Group favored
4	S10	K032201	Earth science	C	Female-male	Male
8	S4	K095601	Physical science	C	Hispanic-White	White
	S7	K102301	Earth science	CC	Black-White	Black
	S10	K096101	Life science	CC	Female-male	Male
	S10	K095301	Physical science	C	Female-male	Male
	S10	K092901	Life science	C	Female-male	Female
	S13	K036201	Physical science	C	Hispanic-White	White
	S15	K064501	Life science	CC	Female-male	Female
12	S4	K100101	Earth science	CC	Hispanic-White	White
	S4	K096401	Physical science	C	Female-male	Male
	S4	K092001	Earth science	CC	Hispanic-White	White
	S7	K105601	Earth science	C	Female-male	Male
	S8	K041305	Life science	C	Female-male	Female
	S9	K102301	Earth science	CC	Black-White	Black
	S10	K091801	Earth science	C	Female-male	Male
	S11	K047401	Physical science	CC	Black-White	White
	S12	K048901	Life science	CC	Hispanic-White	White
	S12	K048801	Earth science	C	Female-male	Male
	S14	K053901	Life science	CC	Female-male	Female
	S14	K053601	Life science	CC	Black-White	Black
	S14	K053601	Life science	CC	Female-male	Female
	S17	K073801	Physical science	CC	Female-male	Male
	S17	K073101	Earth science	C	Female-male	Male
	S18	K074201	Physical science	C	Female-male	Male
SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2005 Science Assessment.

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