About the Assessment: Target Population and Sample Size

The schools and students participating in NAEP assessments are selected to be representative of all schools nationally and of public schools at the state level. Samples of schools and students are drawn from participating states and from the District of Columbia and Department of Defense schools. While results for students assessed in Alaska, the District of Columbia, Kansas, Nebraska, and Vermont contributed to the results for the nation at grades 4 and 8, sample sizes were not large enough to report results for these states/jurisdictions separately. At grades 4 and 8, the results from the assessed students are combined to provide accurate estimates of the overall performance of students in the nation and in individual states and other jurisdictions. States with districts participating in the Trial Urban District Assessments have larger sample sizes.

While national results reflect the performance of students in both public schools and nonpublic schools (i.e., private schools, Bureau of Indian Education schools, and Department of Defense schools), state-level results reflect the performance of public school students only. Results are reported separately for Department of Defense schools in state tables and maps. More information on sampling can be found in NAEP Technical Documentation.

The sample of students in the participating TUDA school districts is an extension of the sample of students who would usually be selected by NAEP as part of state and national samples. Results for students in the TUDA samples are also included in state and national samples with appropriate weighting. For example, the results reported for students in Boston also contribute to the results reported for Massachusetts and to the results for the nation.

Student sample sizes and target populations in NAEP science at grade 8, by state/jurisdiction: 2009
State/jurisdiction	Sample size	Target population
Nation	154,700	3,843,000
Public	149,900	3,504,000
Private	3,100	331,000
Alabama	2,700	53,000
Alaska	—	—
Arizona	2,900	73,000
Arkansas	2,700	33,000
California	7,400	469,000
Colorado	2,800	54,000
Connecticut	2,800	42,000
Delaware	2,800	9,000
Florida	4,500	180,000
Georgia	3,600	109,000
Hawaii	2,900	12,000
Idaho	3,000	20,000
Illinois	4,200	154,000
Indiana	2,800	77,000
Iowa	2,700	33,000
Kansas	—	—
Kentucky	3,800	47,000
Louisiana	2,600	45,000
Maine	2,700	14,000
Maryland	3,500	58,000
Massachusetts	3,800	72,000
Michigan	3,500	117,000
Minnesota	3,000	60,000
Mississippi	2,900	37,000
Missouri	2,800	64,000
Montana	2,700	11,000
Nebraska	—	—
Nevada	2,900	32,000
New Hampshire	2,600	15,000
New Jersey	2,800	100,000
New Mexico	2,600	23,000
New York	3,900	198,000
North Carolina	4,500	112,000
North Dakota	2,300	7,000
Ohio	3,700	129,000
Oklahoma	2,800	44,000
Oregon	2,900	42,000
Pennsylvania	3,700	127,000
Rhode Island	2,800	11,000
South Carolina	2,900	50,000
South Dakota	2,900	9,000
Tennessee	3,000	75,000
Texas	6,200	322,000
Utah	3,000	38,000
Vermont	—	—
Virginia	2,900	90,000
Washington	2,900	75,000
West Virginia	3,000	23,000
Wisconsin	3,600	61,000
Wyoming	1,900	6,000
Other jurisdictions
BIE¹	100	2,000
District of Columbia	—	—
DoDEA²	1,600	5,000
— Not available. ¹ Bureau of Indian Education. ² Department of Defense Education Activity (overseas and domestic schools). NOTE: The sample size is rounded to the nearest hundred. The target population is rounded to the nearest thousand. Data for BIE and DoDEA schools are counted in the overall nation total, but not in the nation (public) total. Data for the District of Columbia public schools are counted, along with the states, in nation (public). Detail may not sum to totals because of rounding. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2009 Science Assessment.