UMD Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/3
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Item READING IN PRINT AND DIGITALLY: PROFILING AND INTERVENING IN UNDERGRADUATES’ MULTIMODAL TEXT PROCESSING, COMPREHENSION, AND CALIBRATION(2019) Singer Trakhman, Lauren Melissa; Alexander, Patricia A; Human Development; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)As a consequence of today’s rapid-paced society and ever-changing technologies, students are frequently called upon to process texts in print and digitally. Further, multimodal texts are standard in textbooks and foundational to learning. Nonetheless, little is understood about the effects of reading multimodal texts in print or digitally. In Study I, the students read weather and soil passages in print and digitally. These readings were taken from an introductory geology textbook that incorporated various graphic displays. While reading, novel data-gathering measures and procedures were used to capture real-time behaviors. As students read in print, their behaviors were recorded by a GoPro@ camera and tracked by the movement of a pen. When reading digitally, students’ actions were recorded by Camtasia@ Screen Capture software and by the movement of the screen cursor used to indicate their position in the text. After reading, students answered comprehension questions that differ in specificity (i.e., main idea to key concepts) that cover content from three sources: text only; visual only; and, both text and visual. Finally, after reading in each medium, undergraduates rated their performance on the comprehension measure on a scale of 0-100 for each passage. The accuracy of these ratings formed the basis of the calibration score. The processing data were analyzed using Latent Class Analysis. In Study II, an intervention aimed at improving students’ comprehension and calibration when reading digitally were introduced to participants from Study I who returned to the lab about two weeks later. Next, the undergraduates repeated the procedure for digital reading outlined in Study I with a passage on volcanoes. In Study I, students performed better when reading in print and spent more time with the text but were better calibrated when reading digitally. Three clusters were identified for the print data, and three clusters were identified for the digital data. Cluster movement across mediums suggests that some participants treat digital texts differently than when reading in print. After the intervention in Study II, comprehension scores and duration increased but calibration accuracy scores worsened. The LCA revealed three clusters, each showing improvement in processing behaviors, comprehension, or reading duration.Item INVESTIGATION OF ALTERNATIVE CALIBRATION ESTIMATORS IN THE PRESENCE OF NONRESPONSE(2017) Han, Daifeng; Valliant, Richard; Survey Methodology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Calibration weighting is widely used to decrease variance, reduce nonresponse bias, and improve the face validity of survey estimates. In the purely sampling context, Deville and Särndal (1992) demonstrate that many alternative forms of calibration weighting are asymptotically equivalent, so for variance estimation purposes, the generalized regression (GREG) estimator can be used to approximate some general calibration estimators with no closed-form solutions such as raking. It is unclear whether this conclusion holds when nonresponse exists and single-step calibration weighting is used to reduce nonresponse bias (i.e., calibration is applied to the basic sampling weights directly without a separate nonresponse adjustment step). In this dissertation, we first examine whether alternative calibration estimators may perform differently in the presence of nonresponse. More specifically, properties of three widely used calibration estimations, the GREG with only main effect covariates (GREG_Main), poststratification, and raking, are evaluated. In practice, the choice between poststratification and raking are often based on sample sizes and availability of external data. Also, the raking variance is often approximated by a linear substitute containing residuals from a GREG_Main model. Our theoretical development and simulation work demonstrate that with nonresponse, poststratification, GREG_Main, and raking may perform differently and survey practitioners should examine both the outcome model and the response pattern when choosing between these estimators. Then we propose a distance measure that can be estimated for raking or GREG_Main from a given sample. Our analytical work shows that the distance measure follows a Chi-square probability distribution when raking or GREG_Main is unbiased. A large distance measure is a warning sign of potential bias and poor confidence interval coverage for some variables in a survey due to omitting a significant interaction term in the calibration process. Finally, we examine several alternative variance estimators for raking with nonresponse. Our simulation results show that when raking is model-biased, none of the linearization variance estimators under evaluation is unbiased. In contrast, the jackknife replication method performs well in variance estimation, although the confidence interval may still be centered in the wrong place if the point estimate is inaccurate.Item Evaluation and Improvement of Temperature Sensitive Paint Data Reduction Process through Analysis of Tunnel Data(2012) Bhandari, Pratik; Yu, Kenneth H.; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)A data reduction process for a temperature sensitive paint heat transfer measurement system in use at the US Air Force Hypervelocity Wind Tunnel No. 9 has been evaluated using a set of data gathered from tests on a generic hypersonic waverider model. Discrepancies were observed between heat transfer results calculated using temperature sensitive paint based measurements as compared to results calculated using conventional thermocouple measurements at specific locations on the test article. Paint thermophysical property estimates were made and utilized in a series of finite element models to analyze paint behavior. These models were used to perform a sensitivity analysis on system parameters. Key identified parameters were used to perform a non-dimensional analysis of the tunnel data. Based on this analysis, discrepancy areas were identified and a novel two-calibration data reduction process was developed that mitigated the severity of some observed discrepancies and showed the potential for future improvements.Item Adult Readers' Calibration of Word Learning(2011) Parkinson, Meghan; Alexander, Patricia A; Human Development; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The current study examined undergraduates' metacognitive processes during word learning, a crucial component of building representations of key concepts from text. Noticing the need to construct meaning for unknown words requires metacognitive monitoring. Constructing meanings for those words requires regulation of cognition. Fukkink (2005) provided a model for word learning, based on think aloud data that represented a series of metacognitive activities word learners engaged in when faced with an unknown word. The evaluation process within Fukkink's (2005) model related to the judgments learners made about new word meanings and how accurate they believed those judgments to be. A specific aspect of metacognitive evaluation is calibration, or the accuracy with which learners asses their knowledge on a particular cognitive task (Glenberg & Epstein, 1985; Lichtenstein & Fischhoff, 1977). The current study more closely examined word learning and calibration, while addressing some gaps in the literature and offering a model of influences on word learning to complement Fukkink's process model. The current study sought to answer questions related to the following goals: 1. To determine the influence of several factors related to adult readers' word learning and calibration of word learning. 2. To assess empirical evidence relative to a model of reading skill, vocabulary knowledge, passage comprehension, and metacognitive evaluation related to word learning using methods that directly measure word learning and metacognitive evaluation. 3. To determine which text factors influenced the ease with which word learners could derive meaning while reading and evaluate their level of performance on a word knowledge test. A measured variable path analysis showed a similar goodness of fit for both the incidental word learning condition and the intentional word learning condition. Prior word knowledge was found to be positively related to judgments of learning, but negatively related to calibration of word learning within the path model. Think-aloud data did not illuminate a connection between passage comprehension, strategic processing, and word learning. However, think-aloud data did reveal that students who decreased in performance from word knowledge pretest to posttest self-reported challenge while reading more frequently than other students. Finally, repeated-measures ANOVAs revealed differences in passage comprehension and JOLs between passages, prompting an analysis of specific text features underlying text difficulty that were not represented with a readability formula.Item Adaptation in Standard CMOS Processes with Floating Gate Structures and Techniques(2007-04-25) Wong, Yanyi Liu; Abshire, Pamela A; Abshire, Pamela A; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)We apply adaptation into ordinary circuits and systems to achieve high performance, high quality results. Mismatch in manufactured VLSI devices has been the main limiting factor in quality for many analog and mixed-signal designs. Traditional compensation methods are generally costly. A few examples include enlarging the device size, averaging signals, and trimming with laser. By applying floating gate adaptation to standard CMOS circuits, we demonstrate here that we are able to trim CMOS comparator offset to a precision of 0.7mV, reduce CMOS image sensor fixed-pattern noise power by a factor of 100, and achieve 5.8 effective number of bits (ENOB) in a 6-bit flash analog-to-digital converter (ADC) operating at 750MHz. The adaptive circuits generally exhibit special features in addition to an improved performance. These special features are generally beyond the capabilities of traditional CMOS design approaches and they open exciting opportunities in novel circuit designs. Specifically, the adaptive comparator has the ability to store an accurate arbitrary offset, the image sensor can be set up to memorize previously captured scenes like a human retina, and the ADC can be configured to adapt to the incoming analog signal distribution and perform an efficient signal conversion that minimizes distortion and maximizes output entropy.Item Structure from Motion on Textures: Theory and Application to Calibration(2005-04-04) Baker, Patrick Terry; Aloimonos, Yiannis J; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation introduces new mathematical constraints that enable us, for the first time, to investigate the correspondence problem using texture rather than point and lines. These three multilinear constraints are formulated on parallel equidistant lines embedded in a plane. We choose these sets of parallel lines as proxies for fourier harmonics embedded on a plane as a sort of ``texture atom''. From these texture atoms we can build up arbitrarily textured surfaces in the world. If we decompose these textures in a Fourier sense rather than as points and lines, we use these new constraints rather than the standard multifocal constraints such as the epipolar or trifocal. We propose some mechanisms for a possible feedback solution to the correspondence problem. As the major application of these constraints, we describe a multicamera calibration system written in C and MATLAB which will be made available to the public. We describe the operation of the program and give some preliminary results.