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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 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
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
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
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
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.