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 4, by state/jurisdiction: 2009
State/jurisdiction	Sample size	Target population
Nation	160,000	3,824,000
Public	155,000	3,485,000
Private	2,800	330,000
Alabama	2,700	56,000
Alaska	—	—
Arizona	3,100	78,000
Arkansas	2,900	37,000
California	7,600	444,000
Colorado	2,800	55,000
Connecticut	2,800	41,000
Delaware	2,800	9,000
Florida	4,800	186,000
Georgia	4,100	117,000
Hawaii	2,800	13,000
Idaho	3,100	21,000
Illinois	4,300	146,000
Indiana	2,800	76,000
Iowa	2,900	34,000
Kansas	—	—
Kentucky	3,900	48,000
Louisiana	2,900	53,000
Maine	2,700	13,000
Maryland	3,600	56,000
Massachusetts	3,900	71,000
Michigan	3,500	117,000
Minnesota	3,400	62,000
Mississippi	2,800	39,000
Missouri	2,800	63,000
Montana	2,700	10,000
Nebraska	—	—
Nevada	3,100	32,000
New Hampshire	2,700	15,000
New Jersey	2,900	102,000
New Mexico	2,900	25,000
New York	4,100	194,000
North Carolina	4,600	105,000
North Dakota	2,100	7,000
Ohio	3,600	126,000
Oklahoma	2,900	46,000
Oregon	2,900	39,000
Pennsylvania	3,700	121,000
Rhode Island	2,500	10,000
South Carolina	3,000	53,000
South Dakota	2,800	9,000
Tennessee	3,000	75,000
Texas	6,500	318,000
Utah	3,400	42,000
Vermont	—	—
Virginia	3,000	86,000
Washington	3,200	75,000
West Virginia	2,800	20,000
Wisconsin	3,900	59,000
Wyoming	2,000	7,000
Other jurisdictions
BIE¹	100	3,000
District of Columbia	—	—
DoDEA²	2,100	7,000
— 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.