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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.

National and State
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
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
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
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
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.