In reaction to such past defects of educational research, the Institute of Educational Sciences has recently instituted rigorous standards for data gathering, including an insistence on random assignments of students to experimental and control groups, on the pattern of good medical research. These are admirable advances. The more reliable the data we obtain are, the more reliable our theories will be. But good theory is not to be confused with good data-gathering techniques alone. The need for a deep general analysis is not obviated by even the best data-gathering techniques. The random assignment of students into control groups and experimental groups is an admirable method for gaining higher confidence in statistical results but cannot by itself explain the underlying reasons for the statistical results nor by itself allow confident predictions that they will be repeated in new circumstances.