Two-phase designs in epidemiological studies of autism prevalence introduce methodological complications that can severely limit the precision of resulting estimates. If the assumptions used to derive the prevalence estimate are invalid or if the uncertainty surrounding these assumptions is not properly accounted for in the statistical inference…

Although often ignored, reliability is critical when interpreting study effects and test results. Accordingly, this article focuses on the most commonly used estimate of reliability, internal consistency coefficients, with emphasis on coefficient alpha. An interpretive framework is provided for applied researchers and others seeking a conceptual…

The relationship between intelligence and personality has been of scientific interest for over 100 years. However, most contemporary estimates of these relationships are limited because they do not separate the variance due to general and narrow cognitive abilities. This study demonstrates that this methodological oversight can distort estimates…

The AP Course Audit utilizes a criterion-based professional judgment method of analysis within a nested multi-step review process. The overall goal of the methodology is to yield a final judgment on each syllabus that is ultimately valid. While reviewer consistency is an important consideration, the most important goal is to reach a final judgment…

Because surveys now can be implemented with relative ease and little cost, many researchers are overlooking the basic principles of survey research. This chapter discusses sources of error that researchers should consider when conducting a survey, and gives readers basic suggestions for reducing error. (Contains 1 table and 1 figure.)

The extent of error likely to occur with each of several approximations for the standard deviation, internal consistency reliability, and the standard error of measurement is analyzed. Approximations were compared with exact statistics obtained on 85 different classroom tests constructed and administered by professors in a variety of fields. Means…

Classification studies are important for practitioners who need to identify individuals for specialized treatment or intervention. When interventions are irreversible or misclassifications are costly, information about the proficiency of different classification procedures becomes invaluable. This study furnishes information about the relative…