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A Monte Carlo Study of the Robustness and Power Associated with Selected Tests of Variance Equality when Distributions are Non-Normal and Dissimilar in Form

Description: When selecting a method for testing variance equality, a researcher should select a method which is robust to distribution non-normality and dissimilarity. The method should also possess sufficient power to ascertain departures from the equal variance hypothesis. This Monte Carlo study examined the robustness and power of five tests of variance equality under specific conditions. The tests examined included one procedure proposed by O'Brien (1978), two by O'Brien (1979), and two by Conover, Johnson, and Johnson (1981). Specific conditions included assorted combinations of the following factors: k=2 and k=3 groups, normal and non-normal distributional forms, similar and dissimilar distributional forms, and equal and unequal sample sizes. Under the k=2 group condition, a total of 180 combinations were examined. A total of 54 combinations were examined under the k=3 group condition. The Type I error rates and statistical power estimates were based upon 1000 replications in each combination examined. Results of this study suggest that when sample sizes are relatively large, all five procedures are robust to distribution non-normality and dissimilarity, as well as being sufficiently powerful.
Date: August 1990
Creator: Hardy, James C. (James Clifford)
Partner: UNT Libraries
open access

A Computer Assisted Drill and Practice System for Introductory Statistics Instruction

Description: To supplement college introductory statistics instruction, an interactive drill system was developed and implemented on a Hewlett- Packard 2000 timesharing computer. Unlimited practice in basic procedures and algorithms was provided over 38 topics including Chi-square, correlational methods, and one-way analysis of variance. Validation of intermediate computational steps was provided, and more difficult or remedial problems sets were made available. Optional files recorded performance data. Four support programs initialized performance files and generated summary reports. Extensive documentation and a library of reusable subroutines were designed to assist future authors to expand the system. The drill and practice system was made generally available to all university departments and students.
Date: May 1979
Creator: Ellis, Richard George
Partner: UNT Libraries
open access

The Evaluation and Control of the Changes in Basic Statistics Encountered in Grouped Data

Description: This dissertation describes the effect that the construction of frequency tables has on basic statistics computed from those frequency tables. It is directly applicable only to normally distributed data summarized by Sturges' Rule. The purpose of this research was to identify factors tending to bias sample statistics when data are summarized, and thus to allow researchers to avoid such bias. The methodology employed was a large scale simulation where 1000 replications of samples of size n = 2 ᵏ⁻¹ for 2 to 12 were drawn from a normally distributed population with a mean of zero and a standard deviation of one. A FORTRAN IV source listing is included. The report concludes that researchers should avoid the use of statistics computed from frequency tables in cases where raw data are available. Where the use of such statistics is unavoidable, the researchers can eliminate their bias by the use of empirical correction factors provided in the paper. Further research is suggested to determine the effect of summarization of data drawn from various non-normal distributions.
Date: May 1979
Creator: Scott, James P.
Partner: UNT Libraries
open access

The 2010 Decennial Census: Background and Issues

Description: The U.S. Constitution--Article 1, Section 2, clause 3, as modified by Section 2 of the Fourteenth Amendment--requires a population census every 10 years, to serve as the basis for reapportioning seats in the House of Representatives. Decennial census data also are used for within-state redistricting and in certain formulas that determine the annual distribution of more than $400 billion dollars in federal and state funds. This report discusses the major innovations that were planned for the 2010 census, problems encountered with the attempt to automate certain census field operations, the persistent differential census undercount of less advantaged groups in the population, and efforts to ensure an equitable census.
Date: May 24, 2010
Creator: Williams, Jennifer D.
Partner: UNT Libraries Government Documents Department
open access

The 2010 Decennial Census: Background and Issues

Description: This report summarizes the information and background of the 2010 census. The report outlines what the census is and why it is necessary. Moreover, it describes the new methods used and the issues encountered by using those methods.
Date: May 24, 2010
Creator: Williams, Jennifer D.
Partner: UNT Libraries Government Documents Department
open access

The 2010 Decennial Census: Background and Issues

Description: This report discusses the major innovations that were planned for the 2010 Census, problems encountered in the attempt to automate certain decennial field operations, issues of census accuracy and coverage, and efforts to ensure an equitable count.
Date: April 27, 2009
Creator: Williams, Jennifer D.
Partner: UNT Libraries Government Documents Department
open access

Fiscal disparities : central cities & suburbs, 1981

Description: The ACIR Library is composed of publications that study the interactions between different levels of government. This document addresses fiscal disparities for central cities and suburbs in 1981.
Date: August 1984
Creator: United States. Advisory Commission on Intergovernmental Relations.
Partner: UNT Libraries Government Documents Department
open access

Accuracy and reliability of China's energy statistics

Description: Many observers have raised doubts about the accuracy and reliability of China's energy statistics, which show an unprecedented decline in recent years, while reported economic growth has remained strong. This paper explores the internal consistency of China's energy statistics from 1990 to 2000, coverage and reporting issues, and the state of the statistical reporting system. Available information suggests that, while energy statistics were probably relatively good in the early 1990s, their quality has declined since the mid-1990s. China's energy statistics should be treated as a starting point for analysis, and explicit judgments regarding ranges of uncertainty should accompany any conclusions.
Date: September 14, 2001
Creator: Sinton, Jonathan E.
Partner: UNT Libraries Government Documents Department
open access

Measurement Disturbance Effects on Rasch Fit Statistics and the Logit Residual Index

Description: The effects of random guessing as a measurement disturbance on Rasch fit statistics (unweighted total, weighted total, and unweighted ability between) and the Logit Residual Index (LRI) were examined through simulated data sets of varying sample sizes, test lengths, and distribution types. Three test lengths (25, 50, and 100), three sample sizes (25, 50, and 100), two item difficulty distributions (normal and uniform), and three levels of guessing (no guessing (0%), 25%, and 50%) were used in the simulations, resulting in 54 experimental conditions. The mean logit person ability for each experiment was +1. Each experimental condition was simulated once in an effort to approximate what could happen on the single administration of a four option per item multiple choice test to a group of relatively high ability persons. Previous research has shown that varying item and person parameters have no effect on Rasch fit statistics. Consequently, these parameters were used in the present study to establish realistic test conditions, but were not interpreted as effect factors in determining the results of this study.
Date: August 1997
Creator: Mount, Robert E. (Robert Earl)
Partner: UNT Libraries
open access

The 2010 Decennial Census: Background and Issues

Description: This report summarizes the information and background of the 2010 census. The report outlines what the census is and why it is necessary. Moreover, it describes the new methods used and the issues encountered by using those methods.
Date: October 18, 2012
Creator: Williams, Jennifer D.
Partner: UNT Libraries Government Documents Department

A Comparison of Five Robust Regression Methods with Ordinary Least Squares: Relative Efficiency, Bias and Test of the Null Hypothesis

Description: A Monte Carlo simulation was used to generate data for a comparison of five robust regression estimation methods with ordinary least squares (OLS) under 36 different outlier data configurations. Two of the robust estimators, Least Absolute Value (LAV) estimation and MM estimation, are commercially available. Three authormodified variations on MM were also included (MM1, MM2, and MM3). Design parameters that were varied include sample size (n=60 and n=180), number of independent predictor variables (2, 3 and 6), outlier density (0%, 5% and 15%) and outlier location (2x,2y s, 8x8y s, 4x,8y s and 8x,4y s). Criteria on which the regression methods were measured are relative efficiency, bias and a test of the null hypothesis. Results indicated that MM2 was the best performing robust estimator on relative efficiency. The best performing estimator on bias was MM1. The best performing regression method on the test of the null hypothesis was MM2. Overall, the MM-type robust regression methods outperformed OLS and LAV on relative efficiency, bias, and the test of the null hypothesis.
Access: Restricted to UNT Community Members. Login required if off-campus.
Date: August 2001
Creator: Anderson, Cynthia, 1962-
Partner: UNT Libraries
open access

The 2010 Decennial Census: Background and Issues

Description: This report summarizes the information and background of the 2010 census. The report outlines what the census is and why it is necessary. Moreover, it describes the new methods used and the issues encountered by using those methods.
Date: February 3, 2011
Creator: Williams, Jennifer D.
Partner: UNT Libraries Government Documents Department
open access

Internet and E-Commerce Statistics: What They Mean and Where to Find Them on the Web

Description: Statistics indicating Internet usage are imprecise. It is difficult to measure the scale of the Internet (or the World Wide Web), calculate the number and types of users (age, sex, race, gender, location, etc.), or forecast future growth. This report discusses the inherent complexities of estimating Internet and electronic commerce growth and describes various types of Internet statistics, discussing how to evaluate them and providing Web addresses for locating them. In addressing these topics, it is important to understand how the statistics are compiled, how they are used, and what their limitations are.
Date: October 24, 2000
Creator: Tehan, Rita
Partner: UNT Libraries Government Documents Department
open access

A Short Primer on Collecting and Analyzing Energy R&D Statistics

Description: This report presents a short overview of various data sources available for understanding investment levels in energy research and development (R&D). The report describes some of the strengths and weaknesses of these data sources. The report also discusses some issues that still need to be resolved in using energy R&D statistics for decision-making purposes.
Date: February 1, 2000
Creator: Dooley, James J.
Partner: UNT Libraries Government Documents Department
open access

Selected Statistics relating to Firearms

Description: This report describes the statistics concerning due to firearms. For these statistics, the United States has two sources: The U.S public health service, bureau of vital statistics, and the federal bureau of investigation.
Date: June 21, 1968
Creator: Olguin, Mary
Partner: UNT Libraries Government Documents Department
open access

Attenuation of the Squared Canonical Correlation Coefficient Under Varying Estimates of Score Reliability

Description: Research pertaining to the distortion of the squared canonical correlation coefficient has traditionally been limited to the effects of sampling error and associated correction formulas. The purpose of this study was to compare the degree of attenuation of the squared canonical correlation coefficient under varying conditions of score reliability. Monte Carlo simulation methodology was used to fulfill the purpose of this study. Initially, data populations with various manipulated conditions were generated (N = 100,000). Subsequently, 500 random samples were drawn with replacement from each population, and data was subjected to canonical correlation analyses. The canonical correlation results were then analyzed using descriptive statistics and an ANOVA design to determine under which condition(s) the squared canonical correlation coefficient was most attenuated when compared to population Rc2 values. This information was analyzed and used to determine what effect, if any, the different conditions considered in this study had on Rc2. The results from this Monte Carlo investigation clearly illustrated the importance of score reliability when interpreting study results. As evidenced by the outcomes presented, the more measurement error (lower reliability) present in the variables included in an analysis, the more attenuation experienced by the effect size(s) produced in the analysis, in this case Rc2. These results also demonstrated the role between and within set correlation, variable set size, and sample size played in the attenuation levels of the squared canonical correlation coefficient.
Date: August 2010
Creator: Wilson, Celia M.
Partner: UNT Libraries
open access

How Attitudes towards Statistics Courses and the Field of Statistics Predicts Statistics Anxiety among Undergraduate Social Science Majors: A Validation of the Statistical Anxiety Scale

Description: The aim of this study was to validate an instrument that can be used by instructors or social scientist who are interested in evaluating statistics anxiety. The psychometric properties of the English version of the Statistical Anxiety Scale (SAS) was examined through a confirmatory factor analysis of scores from a sample of 323 undergraduate social science majors enrolled in colleges and universities in the United States. In previous studies, the psychometric properties of the Spanish and Italian versions of the SAS were validated; however, the English version of the SAS had never been assessed. Inconsistent with previous studies, scores on the English version of the SAS did not produce psychometrically acceptable values of validity. However, the results of this study suggested the potential value of a revised two-factor model SAS to measure statistics anxiety. Additionally, the Attitudes Towards Statistics (ATS) scale was used to examine the convergent and discriminant validities of the two-factor SAS. As expected, the correlation between the two factors of the SAS and the two factors of the ATS uncovered a moderately negative correlation between examination anxiety and attitudes towards the course. Additionally, the results of a structural regression model of attitudes towards statistics as a predictor of statistics anxiety suggested that attitudes towards the course and attitudes towards the field of statistics moderately predicts examination anxiety with attitudes towards the course having the greatest influence. It is recommended that future studies examine the relationship between attitudes towards statistics, statistics anxiety, and other variables such as academic achievement and instructional style.
Date: August 2017
Creator: Obryant, Monique J
Partner: UNT Libraries
open access

Supply and Demand for Energy in the United States by States and Regions, 1960 and 1965 (In Four Parts): 2. Utility Electricity

Description: Report issued by the U.S. Bureau of Mines discussing supply and demand data from the energy industry. As stated in the introduction, "in this report, the discussions in the text describe the methods used to develop data deficiencies for inputs to the supply-demand tables" (p. 1). This report includes maps, tables, and illustrations.
Date: 1969
Creator: Hall, Franklin P. & Broderick, Grace N.
Partner: UNT Libraries Government Documents Department
open access

Supply and Demand For Energy in the United States by States and Regions, 1960 and 1965 (In Four Parts): 4. Petroleum and Natural Gas Liquids

Description: Report issued by the U.S. Bureau of Mines discussing state and regional supply and demand data. As stated in the introduction, "the primary purpose of this study is to provide, on a state-by-state basis, petroleum and natural gas liquids industry data that can be (1) integrated into state and regional energy balances by source, form, and consumer sectors, and (2) used to determine interstate and inter-regional energy flows" (p. 1). This report includes maps, tables, and illustrations.
Date: 1969
Creator: Crump, Lulie H. & Yasnowsky, Phillip N.
Partner: UNT Libraries Government Documents Department
open access

Experimental uncertainty estimation and statistics for data having interval uncertainty.

Description: This report addresses the characterization of measurements that include epistemic uncertainties in the form of intervals. It reviews the application of basic descriptive statistics to data sets which contain intervals rather than exclusively point estimates. It describes algorithms to compute various means, the median and other percentiles, variance, interquartile range, moments, confidence limits, and other important statistics and summarizes the computability of these statistics as a function of sample size and characteristics of the intervals in the data (degree of overlap, size and regularity of widths, etc.). It also reviews the prospects for analyzing such data sets with the methods of inferential statistics such as outlier detection and regressions. The report explores the tradeoff between measurement precision and sample size in statistical results that are sensitive to both. It also argues that an approach based on interval statistics could be a reasonable alternative to current standard methods for evaluating, expressing and propagating measurement uncertainties.
Date: May 1, 2007
Creator: Kreinovich, Vladik (Applied Biomathematics, Setauket, New York); Oberkampf, William Louis (Applied Biomathematics, Setauket, New York); Ginzburg, Lev (Applied Biomathematics, Setauket, New York); Ferson, Scott (Applied Biomathematics, Setauket, New York) & Hajagos, Janos (Applied Biomathematics, Setauket, New York)
Partner: UNT Libraries Government Documents Department
open access

Report on the treatment of elderly patients by dialysis and transplantation in Europe

Description: This report discusses the EDTA Registry which is an organization that collects information on patients receiving treatment for end stage rental failure by dialysis and transplantation in over 30 countries in mainland Europe and on the Mediterranean seaboard.
Date: 1988
Creator: Challah, S.
Partner: UNT Libraries Government Documents Department
open access

Coal-Mine Fatalities in the United States, 1924

Description: Report compiled by the U.S. Bureau of Mines including statistics on fatalities in coal mines located in the United States as well as data regarding the various operations (e.g., number of miners employed and average production). The information is organized into tables for comparison and the text draws some overall conclusions in the summary.
Date: 1925
Creator: Adams, William W.
Partner: UNT Libraries Government Documents Department
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