About the Assessment: Participation Rates

The national samples for students at ages 9, 13, and 17 were chosen using a multistage design that involved drawing students from the sampled public and private schools across the country. Within each age group, the results from the assessed students were combined to provide accurate estimates of the overall performance of students in the nation.

Because each school that participated in the assessment, and each student assessed, represents only a portion of the population of interest, disproportionate representation of subgroups in the selected sample may occur. Results must be weighted to account for any such disproportionate representation. This includes oversampling of schools with high concentrations of students from certain racial/ethnic groups and the lower sampling rates of students who attend small schools.

The weighted national school participation rates for the 2012 long-term trend assessments are presented below. National student participation rates for 9-, 13-, and 17-year-old students were 95 percent, 93 percent, and 88 percent, respectively.

To ensure unbiased samples, NAEP statistical standards require that participation rates for original school samples be 70 percent or higher to report national results separately for public and private school students. At all three ages, the school participation rates met the standards for reporting results separately for public schools in 2012 but not for private schools. Catholic school participation rates, however, did meet the standards in 2012 for reporting results separately, so results for Catholic schools are included.

ReadingMathematics

Age 9Age 13Age 17

School and student participation rates in NAEP reading at age 9, by type of school: 2012
Type of school	Student- weighted percent	School- weighted percent	Number of schools participating	Student- weighted percent	Number of students assessed
	School participation			Student participation
Nation	87	82	380	95	8,700
Public	89	90	300	95	7,900
Private	61	59	90	94	800
Catholic	95	93	30	98	400
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 before substitution. Detail may not sum to totals because of rounding. Private schools include Catholic, other religious and nonsectarian private schools. SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2012 Long-Term Trend Reading Assessment.

School and student participation rates in NAEP reading at age 13, by type of school: 2012
Type of school	Student- weighted percent	School- weighted percent	Number of schools participating	Student- weighted percent	Number of students assessed
	School participation			Student participation
Nation	88	81	380	93	8,800
Public	90	90	300	93	7,900
Private	69	63	80	94	900
Catholic	92	92	30	96	500
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 before substitution. 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), 2012 Long-Term Trend Reading Assessment.

School and student participation rates in NAEP reading at age 17, by type of school: 2012
Type of school	Student- weighted percent	School- weighted percent	Number of schools participating	Student- weighted percent	Number of students assessed
	School participation			Student participation
Nation	84	80	370	88	8,800
Public	86	88	320	88	8,100
Private	63	60	50	88	700
Catholic	88	87	10	88	300
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 before substitution. 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), 2012 Long-Term Trend Reading Assessment.