Researchers are traditionally advised to plan for their required sample size such that achieving a sufficient level of statistical power is ensured (Cohen, 1988). While this method helps distinguishing statistically significant effects from the nonsignificant ones, it does not help achieving the higher goal of accurately estimating the actual size…

Statistical tests carry with them a number of assumptions that must be checked. Failing to do so and to report the results of such preliminary analyses introduce a potential threat to the internal validity of a study and to our ability as consumers to put faith in study findings. This article systematically examines the reporting of checks on…

First, we trace the history of second language acquisition (SLA) from early stages in the mid-twentieth century to today. We next consider the status of the field in today's research world with a particular focus on all aspects of methodology and, finally, we take a look at the future and discuss issues related to scientific rigor in light of Open…

Eta-squared (?[superscript 2]) and partial eta-squared (?[subscript p][superscript 2]) are effect sizes that express the amount of variance accounted for by one or more independent variables. These indices are generally used in conjunction with ANOVA, the most commonly used statistical test in second language (L2) research (Plonsky, 2013).…

Learners' self-initiated language learning with mobile technology occurring outside the classroom is often contextualized, heterogeneous, and idiosyncratic. In this study, we propose a time-series clustering methodology for researching informal mobile language learners' learning and development of another language, with a view to unravelling the…

Artificial linguistic systems (ALSs) offer many potential benefits for second language acquisition (SLA) research. Nonetheless, their use in experiments with posttest-only designs can give rise to internal validity problems depending on the baseline that is employed to establish evidence of learning. Researchers in this area often compare…

This study tests the theoretical predictions regarding effects of increasing task complexity (Robinson, 2001a, 2001b, 2007, 2010; Robinson & Gilabert, 2007) for second language (L2) pronunciation. Specifically, we examine whether more complex tasks (a) lead to greater incidence of pronunciation-focused language-related episodes (LREs) and (b)…

Second language (L2) research relies heavily and increasingly on ANOVA (analysis of variance)-based results as a means to advance theory and practice. This fact alone should merit some reflection on the utility and value of ANOVA. It is possible that we could use this procedure more appropriately and, as argued here, other analyses such as…

Studies on L1- and L2-acquisition of German and Dutch have shown that the particles "too/also" and "again" hamper the realization of finiteness while the particle "not" promotes it. In this study the authors ask whether adversative "but" also affects the realization of finiteness. By applying a…

A generative approach to language acquisition is no different from any other in assuming that target language input is crucial for language acquisition. This discussion note addresses the place of input in generative second language acquisition (SLA) research and the perception in the wider field of SLA research that generative SLA…

Adequate reporting of quantitative research about language learning involves careful consideration of the logic, rationale, and actions underlying both study designs and the ways in which data are analyzed. These guidelines, commissioned and vetted by the board of directors of "Language Learning," outline the basic expectations for…

This article explores the role of transfer and Universal Grammar (UG) in second language (L2) phonology by investigating the L2 acquisition of stress/prominence in footless languages, such as Turkish and French, which have fixed word- and phrase-final prominence respectively. It is proposed that once the prosodic constituent Foot is projected in a…

Traditions of statistical significance testing in second language (L2) quantitative research are strongly entrenched in how researchers design studies, select analyses, and interpret results. However, statistical significance tests using "p" values are commonly misinterpreted by researchers, reviewers, readers, and others, leading to…

Although classical statistical techniques have been a valuable tool in second language (L2) research, L2 research questions have started to grow beyond those techniques' capabilities, and indeed are often limited by them. Questions about how complex constructs relate to each other or to constituent subskills, about longitudinal development in…

This article introduces two sophisticated statistical modeling techniques that allow researchers to analyze systematicity, individual variation, and nonlinearity in second language (L2) development. Generalized linear mixed-effects models can be used to quantify individual variation and examine systematic effects simultaneously, and generalized…