Described is the use of fluorometry in an experiment where the fluorescence of riboflavin is specifically quenched when titrated with riboflavin-binding protein. The amount of riboflavin, required by all organisms, in an unknown solution and the dissociation constant of the vitamin-protein complex can be determined using this method. (KR)

Presents a mathematical problem on calculating the length of a groove on a long-playing record. Analyzes the problem-solving stages by using two methods of estimation or calculation. (ASK)

Examines 250 sixth-grade students' understanding of arithmetic average by assessing their understanding of the computational algorithm. Results indicate that the majority of the students knew the "add-them-all-up-and-divide" averaging algorithm, but only half of the students were able to correctly apply the algorithm to solve a…

Attaining computational fluency is an essential part of students' elementary mathematics education. Offers ways of connecting and balancing understanding and procedures and teaching and assessing computational fluency. (Contains 12 references.) (ASK)

The statistical ramifications of using equal weights, as compared to regression-based differential weights, in the estimation of Wechsler Adult Intelligence Scale--Revised (WAIS-R) factor scores were explored using WAIS standardization data, based on 1,880 adults. Differences resulting from the two approaches were substantial, as is discussed.…

Both computers and calculators are limited by architecture, operating system, and software, to some predetermined level of precision within decimal number presentation and calculation. However, there exists a base that produces a terminating decimal. (MM)

Examined role of spontaneous gesture in 2- to 4-year-olds' counting and assessment of counting accuracy. Found that correspondence of children's speech and gesture varied systematically across age. Children adhered to one-to-one correspondence principle in gesture prior to speech. Counting accuracy related to correspondence of speech and gesture,…

Two experiments examined preschoolers' performance on test relying on the uniqueness principle for using evidence from a miscount in inferring a counterfactual cardinal number, with subtests probing associated number-skills. All the 5-year-olds and half the preschoolers passed the test. Results suggest that a crucial preschool step is to start…

Fit indexes were compared with respect to a specific type of model misspecification. Simple structure was violated with some secondary loadings that were present in the true models that were not specified in the estimated models. The c2 test, Comparative Fit Index, Goodness-of-Fit Index, Incremental Fit Index, Nonnormed Fit Index, root mean…

A bias-corrected estimator of noncentrality parameters of covariance structure models is discussed. The approach represents an application of the bootstrap methodology for purposes of bias correction, and utilizes the relation between average of resample conventional noncentrality parameter estimates and their sample counterpart. The…

The choice of constraints used to identify a simple factor model can affect the shape of the likelihood. Specifically, under some nonzero constraints, standard errors may be inestimable even at the maximum likelihood estimate (MLE). For a broader class of nonzero constraints, symmetric normal approximations to the modal region may not be…

Variants of adaptive Bayesian procedures for estimating the 5% point on a psychometric function were studied by simulation. Bias and standard error were the criteria to evaluate performance. The results indicated a superiority of (a) uniform priors, (b) model likelihood functions that are odd symmetric about threshold and that have parameter…

The past two decades have seen a rising trend in the minimum entrance age for kindergarten in the U.S. A little-noticed, but potentially large, consequence of raising the minimum entrance age is that it imposes additional childcare costs for families whose children are forced to stay out of school for an additional year. This paper develops a…

Students should be encouraged to focus on a big mathematical idea and to look for connections between problems and solution strategies. This unified view suggests that the students are developing computational fluency with fractions.

Through a large-scale simulation study, this article compares item parameter estimates obtained by the marginal maximum likelihood estimation (MMLE) and marginal Bayes modal estimation (MBME) procedures in the 3-parameter logistic model. The impact of different prior specifications on the MBME estimates is also investigated using carefully…