¹ The U.S. Department of Education is no longer distinguishing among institutions based on accreditation level as used in previous sample definitions. As a result, NCES now subdivides the postsecondary institution universe into schools that have Title IV federal financial assistance participation agreements with the U.S. Department of Education and those that do not.. (return to text)

² Private for-profit institutions are not included even though they may be Title IV-participating, degree-granting institutions. (return to text)

³ See The Carnegie Foundation for the Advancement of Teaching, A Classification of Institutions of Higher Education (Princeton, NJ: 1994). (return to text)

⁴ However, the institution survey of NSOPF:99 included one question pertinent to teaching assistants, which asked institution respondents to estimate the percentage of undergraduate student credit hours assigned to teaching assistants. This question allows exploration of the issue of using teaching assistants in undergraduate education. (return to text)

⁵ The NSOPF:99 samples are not simple random samples, and therefore simple random sample techniques for estimating sampling error cannot be applied to these data. The DAS takes into account the complexity of the sampling procedures and calculates standard errors appropriate for such samples. The method for computing sampling errors used by the DAS involves approximating the estimator by the linear terms of a Taylor series expansion. The procedure is typically referred to as the Taylor series method. (return to text)

⁶ A Type I error occurs when one erroneously concludes that a difference observed in a sample reflects a true difference in the population from which the sample was drawn. (return to text)

⁷ U.S. Department of Education, National Center for Education Statistics, A Note from the Chief Statistician, no. 2, 1993. (return to text)

⁸ The standard that p < .05/k for each comparison is more stringent than the criterion that the significance level of the comparisons should sum to p < .05. For tables showing the t statistic required to ensure that p < .05/k for a particular family size and degrees of freedom, see Olive Jean Dunn, "Multiple Comparisons Among Means," Journal of the American Statistical Association 56 (1961): 52–64. (return to text)

⁹ More information about ANOVA and significance testing using the F statistic can be found in any standard textbook on statistical methods in the social and behavioral sciences. (return to text)

¹⁰ Cohen, J., Statistical Power Analysis for the Behavioral Sciences (2nd Ed., Hillsdale, NJ: Lawrence Erlbaum Associates, 1998). (return to text)

¹¹ For more information about least squares regression, see Michael S. Lewis-Beck, Applied Regression: An Introduction, Vol. 22 (Beverly Hills, CA: Sage Publications, Inc., 1980); William D. Berry and Stanley Feldman, Multiple Regression in Practice, Vol. 50 (Beverly Hills, CA: Sage Publications, Inc., 1987).(return to text)

¹² The adjustment procedure and its limitations are described in C.J. Skinner, D. Holt, and T.M.F. Smith, eds., Analysis of Complex Surveys (New York: John Wiley & Sons, 1989). (return to text)