Spatial statistical models that use flow and stream distance

We develop spatial statistical models for stream networks that can estimate relationships between a response variable and other covariates, make predictions at unsampled locations, and predict an average or total for a stream or a stream segment. There have been very few attempts to develop valid spatial covariance models that incorporate flow, stream distance, or both. The application of typical spatial autocovariance functions based on Euclidean distance, such as the spherical covariance model, are not valid when using stream distance. In this paper we develop a large class of valid models that incorporate flow and stream distance by using spatial moving averages. These methods integrate a moving average function, or kernel, against a white noise process. By running the moving average function upstream from a location, we develop models that use flow, and by construction they are valid models based on stream distance. We show that with proper weighting, many of the usual spatial models based on Euclidean distance have a counterpart for stream networks. Using sulfate concentrations from an example data set, the Maryland Biological Stream Survey (MBSS), we show that models using flow may be more appropriate than models that only use stream distance. For the MBSS data set, we use restricted maximum likelihood to fit a valid covariance matrix that uses flow and stream distance, and then we use this covariance matrix to estimate fixed effects and make kriging and block kriging predictions.

Writing Motivation of Students with Specific Language Impairments

This study was designed to compare the writing motivation of students with specific language impairments with their non-disabled peers. Due to the cognitive and linguistic demands of the writing process, students with language impairments face unique difficulties during the writing process. It was hypothesized that students with specific language impairments will be more likely to report lower levels of perceived writing competence and be less autonomously motivated to write. Students in grades 3-5 in 11 schools (33 with specific language impairments, 242 non-disabled peers) completed self-report measures, designed from a Self-Determination Theory perspective, which measured the degree that students are intrinsically motivated to write as well as their perceived writing competence. Statistical analyses showed that (1) students with specific language impairments reported lower levels of perceived writing competence and autonomous writing motivation; (2) SLI status was a significant predictor of perceived writing competence after spelling, grade, and gender were controlled; and (3) when spelling, grade, and gender were controlled, perceived writing competence was a significant predictor of autonomous writing motivation, but SLI status was not. The results of this study are expected to inform the current understanding of the relationship between language ability and writing motivation in students with specific language impairments, as well as the design of future writing interventions.

Differentiation in the Content-Area Classroom for English Language Learners

This paper explores the idea of using differentiation strategies in the content-area classroom to improve reading skills and comprehension. In particular, this thesis explores methods and strategies that can be used in the classroom to help address the individual needs of English language learners (ELLs). A broad range of experts in curriculum, differentiation, and English language acquisition were consulted in the development of this review, which synthesizes the research on ELLs’ needs, differentiation, and differentiation strategies for ELL readers. The models for best teaching practices are then placed within a ninth grade language arts unit.

Literacy Research: Issues of Authority, Ownership, and Representation

With the “social turn” of language in the past decade within English studies, ethnographic and teacher research methods increasingly have acquired legitimacy as a means of studying student literacy. And with this legitimacy, graduate students specializing in literacy and composition studies increasingly are being encouraged to use ethnographic and teacher research methods to study student literacy within classrooms. Yet few of the narratives produced from these studies discuss the problems that frequently arise when participant observers enter the classroom. Recently, some researchers have begun to interrogate the extent to which ethnographic and teacher research methods are able to construct and disseminate knowledge in empowering ways (Anderson & Irvine, 1993; Bishop, 1993; Fine, 1994; Fleischer. 1994; McLaren, 1992). While ethnographic and teacher research methods have oftentimes been touted as being more democratic and nonhierarchical than quantitative methods—-which oftentimes erase individuals lived experiences with numbers and statistical formulas—-researchers are just beginning to probe the ways that ethnographic and teacher research models can also be silencing, unreflective, and oppressive. Those who have begun to question the ethics of conducting, writing about, and disseminating knowledge in education have coined the term “critical” research, a rather vague and loose term that proposes a position of reflexivity and self-critique for all research methods, not just ethnography or teacher research. Drawing upon theories of feminist consciousness-raising, liberatory praxis, and community-action research, theories of critical research aim to involve researchers and participants in a highly participatory framework for constructing knowledge, an inquiry that seeks to question, disrupt, or intervene in the conditions under study for some socially transformative end. While critical research methods are always contingent upon the context being studied, in general they are undergirded by principles of non-hierarchical relations, participatory collaboration, problem-posing, dialogic inquiry, and multiple and multi-voiced interpretations. In distinguishing between critical and traditional ethnographic processes, for instance, Peter McLaren says that critical ethnography asks questions such as “[u]nder what conditions and to what ends do we. as educational researchers, enter into relations of cooperation. mutuality, and reciprocity with those who we research?” (p. 78) and “what social effects do you want your evaluations and understandings to have?” (p. 83). In»the same vein, Michelle Fine suggests that critical researchers must move beyond notions of the etic/emic dichotomy of researcher positionality in order to “probe how we are in relation with the contexts we study and with our informants, understanding that we are all multiple in those relations” (p. 72). Researchers in composition and literacy stud¬ies who endorse critical research methods, then, aim to enact some sort of positive transformative change in keeping with the needs and interests of the participants with whom they work.