Physical Sciences and Mathematics Commons^™

Choosing Among Unequals: A Statistical Solution To A Stalemate, Durgesh Chandra Pathak

Durgesh Chandra Pathak

In Uttar Pradesh, a new tradition has been started of selecting B.Ed degree holders for a job in Primary Schools and it has been named "Vishisht BTC". Applying their own logic, the ruling governments use variuos criterion to select the candidates. The basic problem is that they have to choose candidates on the basis of merit of their marks in various exams. Now, it is well-established fact that marking is not similar in all universities/colleges. So for a same exam, there can be much inter-university as well as intra-university variation in marks given to students. The point is that student …

Regressing Scalar Outcomes On Image Predictors Via Functional Principal Component Regression, Philip T. Reiss

Philip T. Reiss

No abstract provided.

The Economic Value Of Improved Environmental Health In Victorian Rivers, Chris Lloyd

Chris J. Lloyd

The non market valuation technique known as choice modelling was used to general benefit estimates for a selection of hypothetical environmental improvements Victorian Rivers. Monetary values were estimated for four attributed of improvements. The relevance of the approach to management and policy issues is demonstrated.

Estimated P-Values In Discrete Models: Asymptotic And Non-Asymptotic Effects, Chris Lloyd

Chris J. Lloyd

The exact null distribution of a P-value typically depends on nuisance parameters unspecified under the null. For discrete models and standard approximate P-values, this dependence can be quite strong. The estimated (or bootstrap) P-value is the exact probability of the P-value being no larger than its observed value, with the null estimate of the nuisance parameter substituted. For continuous models, it is known that such `bootstrap' P-values deviate from uniformity by terms of order m^{-3/2}, where m is a measure of sample size. The main difficulty with discrete models is the breakdown of asymptotics near the boundary. The aim of …

More Powerful Exact Tests Of Equivalence, Chris Lloyd

Chris J. Lloyd

In randomized clinical trials, it is often required to demonstrate that a new medical treatment is neither substantially worse nor better than a standard reference treatment. Formal testing of such `equivalence hypotheses' is typcialyl done by combining two one-sided tests (TOST). A quite diferent strand of research has demonstrated that maximising P-values over nuisance parameters produces optimal tests (Rohmel and Mansmann (1999) and Lloyd (2008a)). In this paper we point out that, even if the one-sided tests are exact and optimal, the TOST will generally be conservative and requires a further adjustment to remove this conservatism. The appropriate procedure is …

Factors Influencing Farmers’ Willingness To Protect Groundwater From Nonpoint Sources Of Pollution In The Lower Bhavani River Basin, Tamil Nadu, India, Sacchidananda Mukherjee

Sacchidananda Mukherjee

Farmers' perceptions about groundwater and drinking water quality are important, which influence their willingness to adopt protection measures either individually or collectively. This study attempts to capture the factors influencing farmers’ perceptions and their willingness to protect groundwater from nonpoint sources of pollution, and their willingness to support the local government to supply drinking water through alternative arrangements. Six villages are identified in the Lower Bhavani River Basin, Tamil Nadu, India on the basis of their long-term groundwater nitrate concentrations and sources of irrigation. A pre-structured questionnaire survey (face-to-face interviews) has been administered to 395 farm-households across six villages during …

Worldwide Variation In The Doubling Time Of Alzheimer's Disease Incidence Rates, Kathryn Ziegler-Graham, Ron Brookmeyer, Elizabeth Johnson, H. Michael Arrighi

Ron Brookmeyer

Background The doubling time is the number of chronological years for the age-specific incidence rate to double in magnitude. Doubling times describe the rate of increase of the risk of Alzheimer's disease (AD) with advancing age. Estimates of doubling times of AD assist in understanding disease etiology and forecasting future disease prevalence. The objective of this study was to investigate regional and gender differences in the doubling of AD age-specific incidence rates.

Methods We identified all studies in the peer review literature that reported age-specific incidence rates for AD. We modeled the logarithm of the incidence rate as a linear …

Simultaneous Confidence Bands For The Coefficient Function In Functional Regression, Philip T. Reiss

Philip T. Reiss

No abstract provided.

Significant Figures, Tony Badrick, Peter Hickman

Tony Badrick

For consistency of reporting the same number of significant figures should be used for results and reference intervals. The choice of the reporting interval should be based on analytical imprecision (measurement uncertainty).

Inferring Group Differences In Brain Connectivity From Functional Magnetic Resonance Images, Philip T. Reiss

Philip T. Reiss

No abstract provided.

Reliability Of Functional Connectivity Networks: How Can We Assess It?, Philip T. Reiss

Philip T. Reiss

No abstract provided.

Locally Adaptive Nonparametric Binary Regression, Sally Wood, Martin Tanner, Wenxin Jiang, Robert Kohn, Remy Cottet

Sally Wood

No abstract provided.

Bayesian Identification, Selection And Estimation Of Functions In High-Dimensional Additive Models, Anastasios Panagiotelis, Michael Smith

Michael Stanley Smith

In this paper we propose an approach to both estimate and select unknown smooth functions in an additive model with potentially many functions. Each function is written as a linear combination of basis terms, with coefficients regularized by a proper linearly constrained Gaussian prior. Given any potentially rank deficient prior precision matrix, we show how to derive linear constraints so that the corresponding effect is identified in the additive model. This allows for the use of a wide range of bases and precision matrices in priors for regularization. By introducing indicator variables, each constrained Gaussian prior is augmented with a …

Efficient Mean Estimation In Log-Normal Linear Models, Haipeng Shen, Zhengyuan Zhu

Zhengyuan Zhu

The T-Mixture Model Approach For Detecting Differentially Expressed Genes In Microarrays, Shuo Jiao, Shunpu Zhang

Shuo Jiao

The finite mixture model approach has attracted much attention in analyzing microarray data due to its robustness to the excessive variability which is common in the microarray data. Pan (2003) proposed to use the normal mixture model method (MMM) to estimate the distribution of a test statistic and its null distribution. However, considering the fact that the test statistic is often of t-type, our studies find that the rejection region from MMM is often significantly larger than the correct rejection region, resulting an inflated type I error. This motivates us to propose the t-mixture model (TMM) approach. In this paper, …

Mapping As A Knowledge Translation Tool For Ontario Early Years Centres: Views From Data Analysts And Managers, Anita Kothari, S. Michelle Driedger, Julia Bickford, Jason Morrison, Michael Sawada, Ian D. Graham, Eric Crighton

Anita Kothari

Background: Local Ontario Early Years Centres (OEYCs) collect timely and relevant local data, but knowledge translation is needed for the data to be useful. Maps represent an ideal tool to interpret local data. While geographic information system (GIS) technology is available, it is less clear what users require from this technology for evidence-informed program planning. We highlight initial challenges and opportunities encountered in implementing a mapping innovation (software and managerial decision-support) as a knowledge translation strategy.

Methods: Using focus groups, individual interviews and interactive software development events, we taped and transcribed verbatim our interactions with nine OEYCs in Ontario, Canada. …

Forecasting By Extrapolation: Conclusions From Twenty-Five Years Of Research, J. Scott Armstrong

J. Scott Armstrong

Sophisticated extrapolation techniques have had a negligible payoff for accuracy in forecasting. As a result, major changes are proposed for the allocation of the funds for future research on extrapolation. Meanwhile, simple methods and the combination of forecasts are recommended.

Communication Of Research On Forecasting: The Journal, J. Scott Armstrong

J. Scott Armstrong

It seems trivial to point out that one of the major goals of the International Institute of Forecasters is to communicate research findings. In particular, the IIF tries to foster communication among researchers, between researchers and practitioners, across nationalities, and across disciplines. We have two major vehicles for this: the annual symposiums and the journal. This editorial examines the results that we have had to date with our journals.

Review Of Daniel Kahnemann, Paul Slovic, And Amos Tversky (Eds.), Judgment Under Uncertainty: Heuristics And Biases, J. Scott Armstrong

J. Scott Armstrong

This book provides a convenient collection of important papers relevant to a subset of judgmental forecasting. My review discusses: (i) the scope of the readings (ii) the importance of the readings (iii) what is new (iv) how the book is organized (v) advice on using the book, and (vi) who should read the book.

Review Of Allen Tough, Intentional Changes: A Fresh Approach To Helping People Change, J. Scott Armstrong

J. Scott Armstrong

Intentional Changes is an important book. It suggests different approaches to the way in which we try to implement change. It provides, as do most important books, much that you will disagree with. Tough’s conclusions are based on studies that are likely to be unknown to you. The book is interesting, well written, and short.

Index Methods For Forecasting: An Application To American Presidential Elections, J. Scott Armstrong, Alfred G. Cúzan

J. Scott Armstrong

Lichtman (2005) reports that the Keys model has been able to pick the winner of every presidential election since 1860, retrospectively through 1980 and prospectively from 1984-2004. Given this record, it seems sensible to examine this index method. We tested how well the Keys model predicted the winner of the popular vote, and also how closely it forecasted the actual percentage of the two-party vote going to the incumbent ticket. The index method performs well compared with regression models. It also offers the opportunity to incorporate many policy variables. Index methods can be applied to various choice problems faced by …

Significance Tests Harm Progress In Forecasting, J. Scott Armstrong

J. Scott Armstrong

Based on a summary of prior literature, I conclude that tests of statistical significance harm scientific progress. Efforts to find exceptions to this conclusion have, to date, turned up none. Even when done correctly, significance tests are dangerous. I show that summaries of scientific research do not require tests of statistical significance. I illustrate the dangers of significance tests by examining an application to the M3-Competition. Although the authors of that reanalysis conducted a proper series of statistical tests, they suggest that the original M3 was not justified in concluding that combined forecasts reduce errors and that the selection of …

Effectiveness Of Monetary Incentives: Mail Surveys To Members Of Multinational Professional Groups, J. Scott Armstrong, J. Thomas Yokum

J. Scott Armstrong

Members of professional groups were much more likely to respond to a mail survey than nonmembers who were also experts in the area (43.7% versus 13.7%). A one-dollar (U.S.)prepaid monetary incentive increased the response rates, and it was as effective for members as for nonmembers (gains of 18.6% and 15.3%, respectively). Surprisingly, the U.S. dollar monetary incentive had a greater effect on foreign than U.S. response rates (gains of 32.6% and 12.9%, respectively).

Review Of Alfie Kohn, No Contest: The Case Against Competition, J. Scott Armstrong

J. Scott Armstrong

Kohn's No Contest reviews empirical research on competition. In fact, much work has been done to determine whether competition is better than cooperation and some work has compared competition with doing the best for oneself. The research comes from many fields, but primarily from education, sports, the performing arts,and psychology. The results have been consistent, clear-cut, and surprising: competition typically results in less creativity, poorer performance, and reduced satisfaction.

How To Make Better Forecasts And Decisions: Avoid Face-To-Face Meetings, J. Scott Armstrong

J. Scott Armstrong

When financial columnist James Surowiecki wrote The Wisdom of Crowds, he wished to explain the successes and failures of markets (an example of a "crowd") and to understand why the average opinion of a crowd is frequently more accurate than the opinions of most of its individual members. In this expanded review of the book, Scott Armstrong asks a question of immediate relevance to forecasters: Are the traditional face-to-face meetings an effective way to elicit forecasts from forecast crowds (i.e. teams)? Armstrong doesn’t believe so. Quite the contrary, he explains why he considers face-to-face meetings a detriment to good forecasting …

Are Null Results Becoming An Endangered Species In Marketing?, Raymond Hubbard, J. Scott Armstrong

J. Scott Armstrong

Editorial procedures in the social and biomedical sciences are said to promote studies that falsely reject the null hypothesis. This problem may also exist in major marketing journals. Of 692 papers using statistical significance tests sampled from the Journal of Marketing, Journal of Marketing Research, and Journal of Consumer Research between 1974 and 1989, only 7.8% failed to reject the null hypothesis. The percentage of null results declined by one-half from the 1970s to the 1980s. The JM and the JMR registered marked decreases. The small percentage of insignificant results could not be explained as being due to inadequate statistical …

Advocacy As A Scientific Strategy: The Mitroff Myth, J. Scott Armstrong

J. Scott Armstrong

A committee created a fictitious author, Ian Mitroff, who published a paper that violated scientific guidelines. The Mitroff paper recommended an advocacy strategy for scientific research; it said that scientists should vigorously defend their initial hypothesis. I use the advocacy strategy to scientifically prove that Mitroff does not exist.

The Panalba Role-Playing Case, J. Scott Armstrong

J. Scott Armstrong

The Panalba-Role Playing Case was designed to get participants to examine their behavior in a situation where their role can lead them to act in a socially irresponsible manner. A description of the case is provided along with instructions to the administrator. Much research has been done on this case, allowing subjects to compare their behavior with that of previous subjects.

Forecasting For Marketing, J. Scott Armstrong, Roderick J. Brodie

J. Scott Armstrong

Research on forecasting is extensive and includes many studies that have tested alternative methods in order to determine which ones are most effective. We review this evidence in order to provide guidelines for forecasting for marketing. The coverage includes intentions, Delphi, role playing, conjoint analysis, judgmental bootstrapping, analogies, extrapolation, rule-based forecasting, expert systems, and econometric methods. We discuss research about which methods are most appropriate to forecast market size, actions of decision makers, market share, sales, and financial outcomes. In general, there is a need for statistical methods that incorporate the manager's domain knowledge. This includes rule-based forecasting, expert systems, …

The Graffiti Solution, J. Scott Armstrong

J. Scott Armstrong

Graffiti is regarded by many as a blight on our cities because it contributes to visual pollution. City governments spend vast sums in an effort to clean the ubiquitous graffiti from urban walls. I suggest that the "cleansing strategy" is an expensive, ineffective way of dealing with the problem; well-known management techniques can solve the problem more efficiently.