Statistics and Probability Commons^™

Iterative Matrix Factorization Method For Social Media Data Location Prediction, Natchanon Suaysom

HMC Senior Theses

Since some of the location of where the users posted their tweets collected by social media company have varied accuracy, and some are missing. We want to use those tweets with highest accuracy to help fill in the data of those tweets with incomplete information. To test our algorithm, we used the sets of social media data from a city, we separated them into training sets, where we know all the information, and the testing sets, where we intentionally pretend to not know the location. One prediction method that was used in (Dukler, Han and Wang, 2016) requires appending one-hot ...

Methodologies For Studying Human-Microclimate Interactions For Resilient, Smart City Decision-Making, Ulrike Passe, Nadia Anderson, Kris De Brabanter, Michael C. Dorneich, Caroline Krejci, Alenka Poplin, Linda Shenk

Ulrike Passe

Creating sustainable, resilient cities requires integrating an understanding of human behavior and decision-making about the built environment within an expanding range of spatial, political, and cultural contexts. Resilience—the ability to survive from and adapt to extreme or sudden stresses—emphasizes the importance of participation by a broad range of stakeholders in making decisions for the future. Smart cities leverage technology and data collected from the community and its stakeholders to inform and support these decisions. Energy usage in cities starts with people interacting with their environments, such as occupants interacting with the buildings in which they live and work ...

Projecting Iowa's Outdoor-Recreation Needs To 1980, Glenn H. Manning, Henry H. Webster, Frederick S. Hopkins Jr., Roy D. Hickman

Research Bulletin (Iowa Agriculture and Home Economics Experiment Station)

Participation in a wide range of outdoor-recreation activities has increased rapidly in Iowa, as elsewhere in the United States, over the last three decades. Substantial evidence supports anticipation of continued increase in such activity for several decades.

Planning for the effective use of available resources to meet rising demand for outdoor recreation requires sound information of several kinds. Data available as a basis for outdoor-recreation planning in Iowa has been limited in both quantity and quality. This study was conducted to provide one kind of information useful for planning purposes. On the basis of a survey of Iowa residents, estimates ...

Analysis Of Crop-Rotation Experiments, With Application To The Iowa Carrington-Clyde Rotation-Fertility Experiments, G. E. Battese, W. A. Fuller, W. D. Shrader

Research Bulletin (Iowa Agriculture and Home Economics Experiment Station)

This report presents a model by which several crop rotations are compared, and optimal fertilization and rotation practices determined. The model is developed with specific applicability to the rotation- fertility experiments at the Carrington-Clyde Experimental Farm near Independence, Iowa. The substitutability of legume meadow and chemical nitrogen fertilizer and the effect of carry-over of applied nitrogen from crop to crop are incorporated into the analysis. The split-plot nature of the rotation- fertility trials is noted, and a transformation of the yield data is employed to create nearly uncorrelated observations. Response functions are estimated for each crop in each rotation. Optimal ...

Using Variance Components To Estimate Power In A Hierarchically Nested Sampling Design, Maria Dzul, Philip M. Dixon, Michael C. Quist, Stephen J. Dinsmore, Michael R. Bower, Kevin P. Wilson, D. Bailey Gaines

Stephen J Dinsmore

We used variance components to assess allocation of sampling effort in a hierarchically nested sampling design for ongoing monitoring of early life history stages of the federally endangered Devils Hole pupfish (DHP) (Cyprinodon diabolis). Sampling design for larval DHP included surveys (5 days each spring 2007–2009), events, and plots. Each survey was comprised of three counting events, where DHP larvae on nine plots were counted plot by plot. Statistical analysis of larval abundance included three components: (1) evaluation of power from various sample size combinations, (2) comparison of power in fixed and random plot designs, and (3) assessment of ...

A Simulation Model Of The Devils Hole Pupfish Population Using Monthly Length-Frequency Distributions, Maria Dzul, Stephen J. Dinsmore, Michael C. Quist, D. Bailey Gaines, Kevin Patrick Wilson, Michael Roy Bower, Philip M. Dixon

Stephen J Dinsmore

The Devils Hole pupfish, Cyprinodon diabolis, is a federally-endangered fish that is endemic to Devils Hole, a discontiguous part of Death Valley National Park in Nye County, Nevada. Due to its status, Devils Hole pupfish monitoring must be non-obtrusive and thereby exclude techniques that require handling fish. Due to a recent decline in pupfish abundance, Devils Hole pupfish managers have expressed a need for a model that describes population dynamics. This population model would be used to identify vulnerable life history stage(s) and inform management actions. We constructed a set of individualbased simulation models designed to explore effects of ...

Identifying Sources Of Error In Surveys Of Devils Hole Pupfish (Cyprinodon Diabolis), Maria Dzul, Michael C. Quist, Stephen J. Dinsmore, Philip M. Dixon, Michael R. Bower, Kevin P. Wilson, D. Bailey Gaines

Stephen J Dinsmore

We assessed four potential sources of error in estimating size of the population of Devils Hole pupfish (Cyprinodon diabolis): net, time of day, diver, and order of diver. Experimental dives (3/day) were conducted during 4 days in July 2009. Effects of the four sources of error on estimates from dive surveys were analyzed using a split-split plot ANOVA. Diver and order of diver had no significant influence on estimates, whereas the effect of presence or absence of a net was significant. Effects of time of day and presence or absence of a net showed a significant interaction with depth ...

Statistical Methods For Automatic Crack Detection Based On Vibrothermography Sequence-Of-Images Data, Ming Li, Stephen D. Holland, William Q. Meeker

Stephen D. Holland

Vibrothermography is a relatively new nondestructive evaluation technique for finding cracks through frictional heat generated from crack surface vibrations under external excitations. The vibrothermography inspection method provides a sequence of infrared images as output. We use a matched filter technique to increase the signal-to-noise ratio of the sequence-of-images data. An automatic crack detection criterion based on the features extracted from the matched filter output greatly increases the sensitivity of the vibrothermography inspection method. In this paper, we develop a three dimensional matched filter for the sequence-of-images data, present the statistical analysis for the matched filter output, and evaluate the probability ...

Quantitative Multi-Inspection-Site Comparison Of Probability Of Detection For Vibrothermography Nondestructive Evaluation Data, Ming Li, Stephen D. Holland, William Q. Meeker

Stephen D. Holland

This paper describes the estimation of probability of detection (POD) for a vibrothermography inspection procedure. The results are based on a large scale experiment on specimens with two different kinds of metal containing fatigue cracks. The specimens were tested independently at three inspection sites: Iowa State University (ISU), Pratt and Whitney (PW) and General Electric (GE). Despite the substantially different vibrothermography configurations and experimental measurement responses, the estimated PODs as function of crack length and dynamic stress were similar for all three inspection sites, which make quantitative POD comparisons possible across different inspection sites.

Estimating Pay Gaps For Workers With Disabilities: Implications From Broadening Definitions And Data Sets, Kevin F. Hallock, Xin Jin, Linda Barrington

Kevin F Hallock

Purpose: To compare pay gap estimates across 3 different national survey data sets for people with disabilities relative to those without disabilities when pay is measured as wage and salary alone versus a (total compensation) definition that includes an estimate of the value of benefits. Method: Estimates of the cost to the employers of employee benefits at the occupational level from an employer survey data set are matched to individual-level data in each of the 3 data sets. Multiple regression techniques are applied to estimate wage and salary and total compensation gaps between full-time men with and without disabilities. Results ...

Discrimination By Gender And Disability Status: Do Worker Perceptions Match Statistical Measures?, Kevin F. Hallock, Wallace Hendricks, Emer Broadbent

Kevin F Hallock

We explore whether perceptions of discrimination are related to ordinary statistical measures. The majority of disabled respondents report feeling some discrimination due to their disability, the majority of women feel some discrimination because of their gender, and a surprising number of men also report some discrimination. We do not find a strong link between perceptions of discrimination and measured discrimination perhaps because those who perceive discrimination feel that it occurs along other dimensions than pay. However, we do find a connection between whether a person feels his or her income is inadequate and measured discrimination for all groups studied.

Strategies To Stabilize Locally Grown Produce For Year-Round Sales: A Feasibility Study, Sam Beattie, Lester Wilson, Aubrey Mendonca, Stéphanie Jung

Stéphanie Jung

Local markets are dependent on fresh-grown products that are available only on a seasonal basis. This project looked at possible ways to preserve fruits and vegetables for profitable sales in the offseason.

Calibration, Error Analysis, And Ongoing Measurement Process Monitoring For Mass Spectrometry, Stephen B. Vardeman, Joanne Wendelberger, Lily Wang

Stephen B. Vardeman

We consider problems of quantifying and monitoring accuracy and precision of measurement in mass spectrometry, particularly in contexts where there is unavoidable day-to-day/period-to-period changes in instrument sensitivity. First, we consider the issue of estimating instrument sensitivity based on data from a typical calibration study. Simple method-of-moments methods, likelihood-based methods, and Bayes methods based on the one-way random effects model are illustrated. Then, we consider subsequently assessing the precision of an estimate of a mole fraction of a gas of interest in an unknown. Finally, we turn to the problem of ongoing measurement process monitoring and illustrate appropriate setup of ...

Modeling And Inference For Measured Crystal Orientations And A Tractable Class Of Symmetric Distributions For Rotations In Three Dimensions, Melissa Ann Bingham, Daniel J. Nordman, Stephen B. Vardeman

Stephen B. Vardeman

Electron backscatter diffraction (EBSD) is a technique used in materials science to study the microtexture of metals, producing data that measure the orientations of crystals in a specimen. We examine the precision of such data based on a useful class of distributions on orientations in three dimensions (as represented by 3×3 orthogonal matrices with positive determinants). Although such modeling has received attention in the statistical literature, the approach taken typically has been based on general “special manifold” considerations, and the resulting methodology may not be easily accessible to nonspecialists. We take a more direct modeling approach, beginning from a ...

Likelihood-Based Statistical Estimation From Quantized Data View Document, Stephen B. Vardeman, Chiang-Sheng Lee

Stephen B. Vardeman

Most standard statistical methods treat numerical data as if they were real (infinite-number-of-decimal-places) observations. The issue of quantization or digital resolution can render such methods inappropriate and misleading. This article discusses some of the difficulties of interpretation and corresponding difficulties of inference arising in even very simple measurement contexts, once the presence of quantization is admitted. It then argues (using the simple case of confidence interval estimation based on a quantized random sample from a normal distribution as a vehicle) for the use of statistical methods based on "rounded data likelihood functions" as an effective way of handling the matter.

Development Programs For One-Shot Systems Using Multiple-State Design Reliability Models, Suntichai Shevasuthisilp, Stephen B. Vardeman

Stephen B. Vardeman

Design reliability at the beginning of a product development program is typically low, and development costs can account for a large proportion of total product cost. We consider how to conduct development programs (series of tests and redesigns) for one-shot systems (which are destroyed at first use or during testing). In rough terms, our aim is to both achieve high final design reliability and spend as little of a fixed budget as possible on development. We employ multiple-state reliability models. Dynamic programming is used to identify a best test-and-redesign strategy and is shown to be presently computationally feasible for at ...

Uniformly Hyper-Efficient Bayes Inference In A Class Of Nonregular Problems, Danial J. Nordman, Stephen B. Vardeman, Melissa Ann Bingham

Stephen B. Vardeman

We present a tractable class of nonregular continuous statistical models where 1) likelihoods have multiple singularities and ordinary maximum likelihood is intrinsically unavailable, but 2) Bayes procedures achieve convergence rates better than n−1 across the whole parameter space. In fact, for every p>1, there is a member of the class for which the posterior distribution is consistent at rate n−puniformly in the parameter.

Likelihood And Bayesian Methods For Accurate Identification Of Measurement Biases In Pseudo Steady-State Processes, Sriram Devanathan, Stephen B. Vardeman, Derrick K. Rollins Sr.

Stephen B. Vardeman

Two new approaches are presented for improved identification of measurement biases in linear pseudo steady-state processes. Both are designed to detect a change in the mean of a measured variable leading to an inference regarding the presence of a biased measurement. The first method is based on a likelihood ratio test for the presence of a mean shift. The second is based on a Bayesian decision rule (relying on prior distributions for unknown parameters) for the detection of a mean shift. The performance of these two methods is compared with that of a method given by Devanathan et al. (2000 ...

Sheppard's Correction For Variances And The "Quantization Noise Model", Stephen B. Vardeman

Stephen B. Vardeman

In this paper, we examine the relevance of Sheppard's correction for variances and (both the original and a valid weak form of) the so-called "quantization noise model" to understanding the effects of integer rounding on continuous random variables. We further consider whether there is any real relationship between the two. We observe that the strong form of the model is not really relevant to describing rounding effects. We demonstrate using simple cases the substantial limitations of the Sheppard correction, and use simple versions of a weak form of the model to establish that there is no real connection between ...

Constructing A Confidence Interval For The Fraction Who Benefit From Treatment, Using Randomized Trial Data, Emily J. Huang, Ethan X. Fang, Daniel F. Hanley, Michael Rosenblum

Johns Hopkins University, Dept. of Biostatistics Working Papers

The fraction who benefit from treatment is defined as the proportion of patients whose potential outcome under treatment is better than that under control. Statistical inference for this parameter is challenging since it is only partially identifiable, even in our context of a randomized trial. We propose and evaluate a new method for constructing a confidence interval for the fraction who benefit, when the outcome is ordinal-valued (with binary outcomes as a special case). This confidence interval procedure is proved to be pointwise consistent. Our method does not require any assumptions about the joint distribution of the potential outcomes, although ...