The postsecondary students eligible for NPSAS:08 were those who attended a NPSAS- eligible institution during the 2007–08 academic year and who were
• enrolled in either (1) an academic program or at least one course for credit that could be applied toward fulfilling the requirements for an academic degree, or (2) an occupational or vocational program that required at least 3 months or 300 clock hours of instruction to receive a degree, certificate, or other formal award;
• not concurrently enrolled in high school; and
Each sampled institution verified as NPSAS-eligible was asked to provide a list of all students who satisfied all the NPSAS eligibility conditions, preferably an “unduplicated” electronic list (i.e., one in which each student’s name appeared only once), together with identifying, classifying, and locating information.
The NPSAS:08 student sample of 138,000 included an augmentation of about 5,000 additional recipients of SMART Grants and ACGs to ensure sufficient numbers of these students for analysis relating to these new sources of student financial aid. The U.S. Department of
Education provided a file of SMART Grant recipients so that students on the enrollment lists could be matched to this file and identified as recipients. Some schools did not have fall 2007 SMART Grant or ACG recipients on the file, but data were available on SMART Grant or ACG recipients from the previous school year.
As student lists were received from institutions, students were sampled by means of
stratified systematic sampling with predetermined sampling rates that varied by student stratum. To eliminate cross-institution duplication, the Social Security numbers of those selected from an institution were compared with Social Security numbers of students who had already been selected from other institutions. Multiplicity adjustments in the sample weighting (described in more detail in section 6.2.1) accounted for the fact that any students who attended more than one institution during the NPSAS year had more than one chance of selection.
Some institutional systems sent in lists for multiple institutions or campuses. If the lists were separate for each institution or campus, then the samples were selected separately and independently. If the lists were combined into one list with no identifier mapping students to institution or campus, then one student sample was selected that represented all of the institutions or campuses included on the list. In such cases, sampling rates were adjusted, and a weight adjustment was made (see section 6.1.1).
Initial student sampling rates were calculated for each sample institution, using sampling rates designed to generate approximately equal probabilities of selection within the ultimate institution-by-student sampling strata (see appendix B). Sometimes these rates were modified, however, as follows:
• The student sampling rates were increased so that the sample size for each sample institution was at least 10 students (if possible) to ensure sufficient yield for variance estimation.
• Student sampling rates were decreased if the sample size was greater than 300.
• To ensure that the desired student sample sizes were achieved, sample yield was
monitored throughout enrollment list collection, and student sampling rates were adjusted periodically for institutions for which sample selection had not yet been performed. These adjustments to the initial sampling rates resulted in some additional variability in the student sampling rates and therefore in some increase in survey design effects (variance inflation; see section 6.4.3).
The planned and achieved sample sizes are reported by student stratum and level of offering (table 5). Also reported is the initial classification of the student sample overall and by institutional type and student stratum (table 6). The achieved sample yield of 137,800 was very close to the targeted 138,050 because institutional participation rates were correctly estimated and the sampling rates throughout the sampling process were persistently monitored and adjusted. Overall, more
baccalaureates, other undergraduate students,14 and doctoral students were selected into the sample
than planned, with fewer ACG, master’s, and other graduate students than planned (for details about sample allocation, see appendix B, section B.4).15
Table 5. Planned and achieved NPSAS:08 student samples, by student stratum and institutional level: 2008
Student stratum1 Institutional level2
Students sampled Number
expected3 achievedNumber 4 Percent5
Total All institutions 138,050 137,800 99.8
Baccalaureate business 4-year 2,500 3,270 131.0
Baccalaureate STEM and SMART
Grant 4-year 3,270 4,660 142.7
Baccalaureate STEM and no SMART
Grant 4-year 2,840 3,100 109.1
Baccalaureate neither STEM nor
SMART Grant 4-year 170 280 164.5
Baccalaureate other 4-year 22,120 18,000 81.4
Baccalaureate all 2-year # 150 #
Other undergraduate SMART Grant Subtotal 580 1,310 226.1
Less-than-2-year # # #
2- to 3-year 10 190 1,745.5
4-year 570 1,110 196.3
Other undergraduate ACG Subtotal 3,590 2,520 70.2
Less-than-2-year # 20 #
2- to 3-year 1,780 600 33.4
4-year 1,800 1,900 105.3
Other undergraduate Subtotal 89,920 91,820 102.1
Less-than-2-year 9,310 8,790 94.4 2- to 3-year 40,390 42,510 105.3
4-year 40,230 40,520 100.7
Master’s 4-year 7,880 6,530 82.8
Doctoral 4-year 3,100 3,760 121.5
Other graduate 4-year 40 470 1,128.6
First-professional 4-year 2,050 1,920 93.9
# Rounds to zero.
1 As expected, the sampling frames misclassified some individual students with respect to baccalaureate, other undergraduate, graduate, and first-professional status; numbers presented in this table are based on the sampling frame classification. The in-state and out-of-state strata have been combined.
2 Institutional level is based on level confirmed by the school during institutional contacting.
3 Based on sample allocation and 2004–05 Integrated Postsecondary Education Data System (IPEDS) file enrollment counts. 4 The student sample was drawn from 1,730 eligible institutions determined to be eligible and providing enrollment lists. 5 Percentage reported reflects the ratio of “achieved” to “expected.”
NOTE: Detail may not sum to totals because of rounding. ACG = Academic Competitiveness Grant; SMART = Science and Mathematics Access to Retain Talent; STEM = science, technology, engineering, or mathematics.
SOURCE: U.S. Department of Education, National Center for Education Statistics, 2007–08 National Postsecondary Student Aid Study (NPSAS:08).
14Other undergraduate students are defined as any undergraduate student not classified as a potential baccalaureate student.
C hapt er 2. D es ign an d M et ho dol og y N PSAS: 08 F ull- sc al e M et ho do logy R epor t 21 2
Table 6. Initial classification of NPSAS:08 student sample, by institutional characteristics and student type: 2008 Institutional characteristic
Total sample1 Student sampling type2, 3 Number Percent
Bachelor’s Other undergraduate Graduate First-professional Number Percent Number Percent Number Percent Number Percent Allinstitutions 137,800 100.0 29,470 100.0 95,650 100.0 10,760 100.0 1,920 100.0 Institutional level Less-than-2-year 8,820 6.4 # # 8,810 9.2 # # # 0.1 2-year 43,460 31.5 150 0.5 43,300 45.3 10 # # 0.1 4-year non-doctorate-granting 37,930 27.5 12,950 44.0 22,880 23.9 2,080 19.3 20 1.1 4-year doctorate-granting 47,590 34.5 16,360 55.5 20,650 21.6 8,680 80.7 1,900 98.8 Institutional control Public 87,470 63.5 17,600 59.7 64,390 67.3 4,900 45.5 590 30.6 Private not-for-profit 32,760 23.8 10,220 34.7 15,560 16.3 5,650 52.5 1,330 69.3 Private for-profit 17,570 12.7 1,640 5.6 15,710 16.4 210 2.0 # 0.1 Type of institution Public less-than-2-year 1,730 1.3 # # 1,730 1.8 # # # # Public 2-year 39,340 28.5 100 0.3 39,230 41.0 10 # # 0.1
Public 4-year non-doctorate-granting 16,120 11.7 5,890 20.0 9,550 10.0 680 6.3 # 0.1 Public 4-year doctorate-granting 30,280 22.0 11,610 39.4 13,880 14.5 4,210 39.2 590 30.4 Private not-for-profit less-than-4-year 2,080 1.5 10 # 2,070 2.2 # # # # Private not-for-profit 4-year non-doctorate-granting 14,200 10.3 5,550 18.8 7,290 7.6 1,360 12.6 10 0.4 Private not-for-profit 4-year doctorate-granting 16,480 12.0 4,660 15.8 6,200 6.5 4,290 39.9 1,330 69.0 Private for-profit less-than-2-year 6,610 4.8 # # 6,610 6.9 # # # 0.1 Private for-profit 2-year-or-more 10,960 8.0 1,640 5.6 9,100 9.5 210 2.0 # 0.1 # Rounds to zero.
1 The student sample was drawn from 1,730 eligible institutions that provided enrollment lists.
2 As expected, the sampling frames misclassified some individual students as to baccalaureate, other undergraduate, graduate, and first-professional status; numbers presented in this table are
based on the sampling frame classification.
3 The 10 baccalaureate strata have been combined, the 6 other undergraduate strata have been combined, and the master’s, doctorate, and other graduate strata have been combined.
NOTE: Detail may not sum to totals because of rounding.