Details of the design and data analysis associated with the 1988 National Assessment of Educational Progress (NAEP) are presented. The 1988 NAEP surveyed American students' knowledge of reading, writing, civics, U.S. history, and geography. Small-scale studies were conducted for mathematics and science. Populations included public school students and private school students (aged 9, 13, and 17 years) as well as students in grades 4, 8, and 12. Geography was surveyed only at grade 12/age 17 years. The objective of these technical notes is to provide information to allow the reader to judge the utility of the design, quality of the NAEP data, reasonableness of the assumptions made, appropriateness of the data analyses, and generalizability of the inferences made from the data. Topics addressed include: development of objectives and items; sample design; assessment instruments; field administration; materials processing and database creation; processing assessment materials; professional scoring; data transcription systems; editing data; quality control of data entry; database products; weighting procedures and estimation of sampling variance; scaling procedures; data analysis for the various subject area assessments; and the statistical summary of the samples and estimates of proficiencies of U.S. students. A total of 204 data tables and 14 figures are provided. Appendices provide: a list of consultants for development of the 1988 NAEP objectives and items; distributions of weight components for the 1988 NAEP samples; contrast codings and estimated effects for 1988 NAEP conditioning variables; 1988 NAEP derived and composite conditioning variables; revision of 1984 NAEP post-stratification weights for grade 4/age 9 years and grade 8/age 13 years; 1988 NAEP item response theory parameters; and NAEP reporting subgroups, composite and derived common background variables, and subject-specific composite and derived reporting variables. A glossary of terms, a list of references cited in the text, and an index are included. (TJH)
Ischemia is localized tissue anemia due to obstruction of the inflow of arterial blood, thus brain ischemia is the condition where insufficient blood is delivered to the brain. Many physiological processes occurring in the brain critically depend on the state of its energy metabolism. The state of brain energy metabolism in turn depends on the delivery of oxygen and glucose to the brain via the bloodstream. Although it comprises only 2% of the total body weight, the human brain consumes 20-25% of the oxygen and up to 70% of the free glucose taken in by the body. The brain respires more intensively than any other organ of the body. The intensity of oxygen consumption by cortical brain tissue much exceeds the demands of other tissues (5.43 mmol 02/g per h versus 3.06 and 4.02 mmol for heart at rest and intensively working, respectively, 2.4 mmol for kidneys, and 1.8 mmol for liver). Oxidative phosphorylation in mitochondria generates 95% of the adenosine triphosphate (ATP) that is formed in the brain. Thus, it is clear why insufficiency of oxygen delivery to brain cells adversely affects brain function. Glucose is the main energy-providing substrate in the brain. The basic pathway of its metabolism in neural tissue is aerobic glycolysis.
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