Introduction: Planned missing designs are relatively new to the field of psychological and developmental research. These designs allow researchers to randomly assign participants to missing data conditions; participants are either randomly selected to receive or not receive particular measures or items during data collection (Little &…

This article enters the debate about the complex and dynamical nature of second language acquisition (SLA) by discussing and commenting on Pallotti's critique of Complex Dynamic Systems Theory (CDST). Pallotti's critique brings to the fore the argument that, due to its anti-reductionist stance, CDST research fails to observe three fundamental…

Single subject (SS) designs are popular in educational and psychological research. There exist several statistical techniques designed to analyze such data and to address the question of whether an intervention has the desired impact. Recently, researchers have suggested that generalized additive models (GAMs) might be useful for modeling…

Many of the mediation analyses reported in the literature are based on concurrent or single-occasion data sets. The 2 overarching themes of the present article are: Results of concurrent mediations are inherently ambiguous, and researchers would be wise to conduct mediations on longitudinal data sets instead. An example included here demonstrates…

Mediation is a causal process that evolves over time. Thus, a study of mediation requires data collected throughout the process. However, most applications of mediation analysis use cross-sectional rather than longitudinal data. Another implicit assumption commonly made in longitudinal designs for mediation analysis is that the same mediation…

Single case designs (SCDs) are short time series that assess intervention effects by measuring units repeatedly over time both in the presence and absence of treatment. For a variety of reasons, interest in the statistical analysis and meta-analysis of these designs has been growing in recent years. This paper proposes modeling SCD data with…

Experimental and quasi-experimental designs are used in educational research to establish causality and develop effective practices. These research designs rely on a counterfactual model that, in simple form, calls for a comparison between a treatment group and a control group. Developers of educational practices often assume that the population…

The strong differences in manifestation, prevalence, and incidence in dyslexia across languages invite studies in specific writing systems. In particular, the question of the role played by emergent literacy in opaque and transparent writing systems remains a fraught one. This research project tested, through a 4-year prospective cohort study, an…

This study examines effects of individual development accounts (IDAs) on household wealth of low-income participants. Methods: This study uses longitudinal survey data from the American Dream Demonstration (ADD) involving experimental design (treatment group = 537, control group = 566). Results: Results from quantile regression analysis indicate…

Structural equation modeling (SEM) is a data-analytic technique that allows researchers to test complex theoretical models. Most published applications of SEM involve analyses of cross-sectional recursive (i.e., unidirectional) models, but it is possible for researchers to test more complex designs that involve variables observed at multiple…

A view of needs assessment consistent with ecological frameworks is presented in this paper. Discussion focuses on intensive and extensive data types, horizontal approaches, and basic assumptions and requirements of convergent analysis. Also discussed are four linking mechanisms used to connect information among data levels used in convergent…

Addresses the use of missing cells in longitudinal research. Gives a sample educational situation involving cohorts and grade levels and uses multiple linear regression for the solution. Discusses applications of longitudinal research wherein logically missing cells occur. (Author/SV)

This article attempts to clarify the Schaie-Baltes controversy dealing with the formulation of adequate developmental research design. Crucial to clarification is distinguishing between description and explanation of developmental change. (MS)

This report presents an analysis blueprint for data provided by the National Education Longitudinal Study of 1988 (NELS:88), a survey system sponsored by the National Center for Education Statistics (NCES). The report will inform beginning NELS:88 data users of the many substantive issues that can be addressed by the data, and it should present…

This article examines LibQUAL+[TM]'s instrument, fundamental assumption, and research approach and proposes a functional/technical model of academic library effectiveness. This expanded view of library effectiveness complements LibQUAL+[TM], emphasizing it to be dependent upon users' experience of service delivery, as LibQUAL+[TM] recognizes.…