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 participating states and from the District of Columbia and Department of Defense schools. 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. 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 standards require 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.

The weighted national school participation rate for the 2011 science assessment at grade 8 was 97 percent (100 percent for public schools, 74 percent for private schools). The weighted student participation rate was 93 percent.

A nonresponse bias analysis was conducted for the grade 8 private school sample. The analysis showed that, while the original responding school samples may have been somewhat different from the entire sample of eligible schools, including substitute schools and adjusting the sampling weights to account for school nonresponse were partially effective in reducing the potential for nonresponse bias. However, some variables examined in the analysis still indicated potential bias after nonresponse adjustments. For instance, smaller schools were somewhat overrepresented in the final private school sample, and the responding sample of private schools contained a higher percentage of Black students and lower percentage of White students than the original sample of eligible private schools.

State 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. With one exception, participation rates for the original samples in the states and jurisdictions participating in the 2011 science assessment at grade 8 were 99 or 100 percent. The participation rate in Colorado was 84 percent.

A nonresponse bias analysis was conducted for the public school sample in Colorado. After sampling weights were adjusted to account for nonresponse, some school characteristics still indicated potential bias. For instance, White students were slightly underrepresented and Hispanic students were slightly overrepresented in the final responding sample. The remaining potential bias associated with student achievement was even larger, however, with the responding sample containing a higher percentage of low-achieving students than the original eligible sample.

Learn more about the sampling design.

National and State

Grade 8

School and student participation rates in NAEP science at grade 8, by state/jurisdiction: 2011
State/jurisdiction	Student- weighted percent	School- weighted percent	Number of schools participating	Student- weighted percent	Number of students assessed
	School participation			Student participation
Nation	97	88	7,290	93	122,000
Public	100	100	6,690	93	119,600
Private	74	70	480	94	800
BIE¹	83	85	60	88	100
Alabama	100	100	110	93	2,300
Alaska	100	98	120	90	2,100
Arizona	99	99	120	93	2,300
Arkansas	100	100	120	94	2,300
California	100	100	220	93	2,500
Colorado	84	87	100	93	1,900
Connecticut	100	100	110	91	2,200
Delaware	100	100	50	92	2,300
Florida	100	100	210	93	2,300
Georgia	100	100	120	93	2,400
Hawaii	100	100	80	93	2,400
Idaho	100	100	110	93	2,400
Illinois	100	100	210	94	3,500
Indiana	100	100	110	94	2,300
Iowa	100	100	130	93	2,200
Kansas	100	100	140	94	2,300
Kentucky	100	100	140	93	3,200
Louisiana	100	100	120	93	2,200
Maine	100	100	130	93	2,200
Maryland	99	99	150	93	2,300
Massachusetts	99	98	140	92	2,300
Michigan	100	100	150	92	2,200
Minnesota	100	100	140	92	2,500
Mississippi	100	100	110	92	2,100
Missouri	100	100	120	93	2,100
Montana	100	98	180	91	2,200
Nebraska	100	100	140	95	2,200
Nevada	100	97	90	93	2,300
New Hampshire	100	100	90	91	2,200
New Jersey	100	100	110	92	2,200
New Mexico	99	99	120	92	2,800
New York	99	100	170	91	3,400
North Carolina	100	100	150	92	2,600
North Dakota	100	99	170	95	1,900
Ohio	100	100	160	93	2,300
Oklahoma	100	100	150	92	2,100
Oregon	99	99	140	93	2,400
Pennsylvania	100	100	160	93	2,300
Rhode Island	100	100	50	92	2,300
South Carolina	100	100	110	94	2,300
South Dakota	100	100	210	95	2,600
Tennessee	100	100	120	92	2,400
Texas	99	100	210	93	2,700
Utah	100	100	110	92	2,400
Vermont	100	100	120	94	1,800
Virginia	100	100	110	94	2,300
Washington	100	100	130	92	2,600
West Virginia	100	100	110	93	2,300
Wisconsin	100	100	150	93	2,100
Wyoming	100	100	90	92	1,800
Other jurisdictions
District of Columbia	100	100	80	88	2,500
DoDEA²	99	95	60	94	1,400
¹ Bureau of Indian Education. ² Department of Defense Education Activity (overseas and domestic schools). NOTE: The number of schools is rounded to the nearest ten. The number of students is rounded to the nearest hundred. The school participation rates are student-weighted percentages before substitution. 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), 2011 Science Assessment.