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About the Assessment: Participation Rates

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 each state and from the District of Columbia and Department of Defense schools. Because each school that participated in the assessment, and each student assessed, represents a portion of the population of interest, the results are weighted to account for the disproportionate representation of the selected sample. Read more technical information about weighting adjustments made at the school and student level.

National participation

To ensure unbiased samples, NAEP requires that participation rates for original school samples be 70 percent or higher to report national results separately for public and private schools. In instances where participation rates meet the 70 percent criteria but fall below 85 percent, a nonresponse bias analysis is conducted to determine if the responding school sample is not representative of the population, thereby introducing the potential for nonresponse bias.

Before substituting new schools for originally sampled schools that declined to participate, the student-weighted national school participation rates for the 2009 reading assessment were 97 percent for grade 4 (100 percent for public schools and 73 percent for private schools), 97 percent for grade 8 (100 percent for public schools and 72 percent for private schools), and 83 percent for grade 12 (86 percent for public schools and 52 percent for private schools). Weighted student participation rates were 95 percent at grade 4, 93 percent at grade 8, and 81 percent at grade 12. The nonresponse bias analysis for private schools at grades 4 and 8 showed that, while the original responding school sample may not have been fully representative, the potential bias was reduced by including substitute schools and by adjusting the sampling weights to account for school nonresponse. At grade 12, the school participation rate for private schools fell below the standard for reporting.

Because the grade 12 weighted student participation rate in public schools was below 85 percent (80 percent), a student nonresponse bias analysis was conducted. That analysis showed that the responding student sample differed from the original student sample with respect to race, relative age, and student disability status. After adjusting the sampling weights to account for student nonresponse, the remaining bias was small, with the nonresponse adjusted estimates for the three identified variables differing from the unadjusted estimates by plus or minus 0.1 percentage points.

State and district participation

Standards established by the National Assessment Governing Board require that school participation rates for the original state samples need to be at least 85 percent for results to be reported. In 2009, all 52 states and jurisdictions, along with all 18 districts participating in the reading assessment at grades 4 and 8 met this participation rate requirement. Because the weighted school participation rate in Illinois was 84.5 percent, a school nonresponse bias analysis was conducted for the grade 12 public school sample in that state. That analysis showed that the potential nonresponse bias was effectively reduced by including substitute schools and adjusting the sampling weights to account for school nonresponse.  The school participation rates for the remaining 10 states all met the required standard with weighted participation rates ranging from 92 to 100 percent. 

Student nonresponse bias analyses were conducted at grade 12 for Connecticut, Florida, Illinois, Iowa, Massachusetts, New Hampshire, New Jersey, South Dakota, and West Virginia, where the student response rate fell below 85 percent. Across these nine states, after nonresponse adjustments, the percentage difference between nonresponse adjusted sample and eligible student sample was 1.3 percent or less. Based on the student characteristics available, there does not appear to be evidence of substantial bias resulting from student nonresponse.

The tables below provide participation rates before substitution.

Learn more about the sampling design.

National and State
School and student participation rates in NAEP reading at grade 12, by state/jurisdiction: 2009
  School participation Student participation
State/jurisdiction Student-
Number of
Number of
     Nation 83 79 1,670 81 51,700
       Public 86 87 1,500 80 48,900
       Private 52 57 170 88 2,700
Arkansas 100 100 100 87 2,700
Connecticut 100 100 100 75 2,800
Florida 100 100 80 80 3,400
Idaho 100 100 100 89 3,100
Illinois 85 94 80 79 2,800
Iowa 100 100 120 84 2,700
Massachusetts 100 100 90 82 3,100
New Hampshire 92 94 60 69 2,200
New Jersey 99 99 90 78 3,200
South Dakota 100 100 130 84 2,700
West Virginia 100 100 90 82 3,000
NOTE: The number of schools is rounded to the nearest ten. The number of students is rounded to the nearest hundred. State results include public schools and public school students only. Eleven states participated in the assessment and met the reporting criteria. Columns of percentages have different denominators. 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 Reading Assessment.