Using the β-binomial distribution to characterize forest health

1995 ◽  
Vol 25 (3) ◽  
pp. 462-469 ◽  
Author(s):  
S.J. Zarnoch ◽  
R.L. Anderson ◽  
R.M. Sheffield
Keyword(s):  
United States ◽  
Binomial Distribution ◽  
Forest Health ◽  
Likelihood Estimation ◽  
The United States ◽  
Parameter Estimates ◽  
Dichotomous Data ◽  
Biological Interpretation ◽  
Dogwood Anthracnose ◽  
Tests Of Hypotheses

The β–binomial distribution is suggested as a model for describing and analyzing the dichotomous data obtained from programs monitoring the health of forests in the United States. Maximum likelihood estimation of the parameters is given as well as asymptotic likelihood ratio tests. The procedure is illustrated with data on dogwood anthracnose infection (caused by Disculadestructive¡) in the southeastern United States. The parameter estimates have important biological interpretation, and tests of hypotheses are more meaningful than traditional statistical analyses. The value of a modeling approach to dichotomous data analysis is emphasized.

Population dynamics of muskrats and mink: investigating contemporary patterns in a classic predator-prey system

2021 ◽  
Author(s):  
Adam A Ahlers ◽  
Timothy P Lyons ◽  
Edward J Heske
Keyword(s):  
United States ◽  
Population Dynamics ◽  
Density Dependence ◽  
American Mink ◽  
Population Cycles ◽  
The United States ◽  
Parameter Estimates ◽  
Predator Prey ◽  
Cycle Lengths ◽  
Southern Half

A well-studied predator-prey relationship between American mink (Neovison vison (Schreber, 1777)) and muskrats (Ondatra zibethicus (Linnaeus, 1766)) in Canada has advanced our understanding of population cycles including the influence of density dependence and lagged responses of predators to prey abundances. However, it is unclear if patterns observed in Canada extend across the southern half of their native range. We used data from the United States to create a 41-year time series of mink and muskrat harvest reports (1970-2011) for 36 states. After controlling for pelt-price effects, we used 2nd order autoregressive and Lomb-Scargle spectral density models to identify the presence and periodicity of muskrat population cycles. Additionally, we tested for evidence of delayed or direct density dependence and for predator-driven population dynamics. Our results suggest muskrat populations may cycle in parts of the United States; however, results varied by modeling approaches with Lomb-Scargle analyses providing more precise parameter estimates. Observed cycle lengths were longer than expected with weak amplitudes and we urge caution when interpreting these results. We did not detect evidence of a predator-prey relationship driven by a lagged numerical response of American mink. American mink and muskrat fur returns were largely correlated across the region suggesting extraneous factors likely synchronize both populations.

scholarly journals Second waves, social distancing, and the spread of COVID-19 across America

2020 ◽  
Vol 5 ◽  
pp. 103 ◽  
Author(s):  
Karl J. Friston ◽  
Thomas Parr ◽  
Peter Zeidman ◽  
Adeel Razi ◽  
Guillaume Flandin ◽  
...  
Keyword(s):  
United States ◽  
Effective Connectivity ◽  
The United States ◽  
Parameter Estimates ◽  
Key Factors ◽  
Strategic Responses ◽  
Social Distancing ◽  
Viral Spread ◽  
Single Region ◽  
Dynamic Causal Model

We recently described a dynamic causal model of a COVID-19 outbreak within a single region. Here, we combine several of these (epidemic) models to create a (pandemic) model of viral spread among regions. Our focus is on a second wave of new cases that may result from loss of immunity—and the exchange of people between regions—and how mortality rates can be ameliorated under different strategic responses. In particular, we consider hard or soft social distancing strategies predicated on national (Federal) or regional (State) estimates of the prevalence of infection in the population. The modelling is demonstrated using timeseries of new cases and deaths from the United States to estimate the parameters of a factorial (compartmental) epidemiological model of each State and, crucially, coupling between States. Using Bayesian model reduction, we identify the effective connectivity between States that best explains the initial phases of the outbreak in the United States. Using the ensuing posterior parameter estimates, we then evaluate the likely outcomes of different policies in terms of mortality, working days lost due to lockdown and demands upon critical care. The provisional results of this modelling suggest that social distancing and loss of immunity are the two key factors that underwrite a return to endemic equilibrium.

The Kerner Commission Report: Did It Incentivize or Cause an Increase in the Production and Hiring of Black PhD Economists in Academia?

2019 ◽  
Vol 46 (4) ◽  
pp. 349-361
Author(s):  
Gregory N. Price
Keyword(s):  
United States ◽  
Negative Binomial ◽  
The United States ◽  
Parameter Estimates ◽  
Research Institution ◽  
Commission Report ◽  
Economics Department ◽  
Kerner Commission ◽  
Education And Employment ◽  
Black Economists

Approximately 50 years ago, the Kerner Commission Report cited pervasive racial discrimination in training, education, and employment as a contributor to Black–White inequality and stratification in the United States. This article considers if the Kerner Commission Report incentivized and possibly caused an increase in the production and hiring of Black PhD economists in academia. With longitudinal data on counts of economic doctorates earned by Black Americans employed in economics departments between 1957 and 2018, we estimate the parameters of count data specifications that accounts for the 1968 Kerner Commission Report dichotomously. Parameter estimates from mixed and fixed effect Poisson, negative binomial, and Poisson quantile specifications suggest that while the Kerner Commission Report generally had a positive effect on the number of Black American economics doctorates employed as faculty, it had no effect on the hiring of Black economists at the typical research institution and PhD-granting economics department. Our results suggest that similar to the Kerner Commission Report characterization of the United States being two separate racially stratified societies, approximately 50 years later research institutions and PhD-granting economics departments in the United States are similarly racially stratified.

scholarly journals Household Debts-and Macroeconomic factors Nexus in the United States: A Cointegration and Vector Error Correction Approach

2014 ◽  
Vol 6 (6) ◽  
pp. 452-465 ◽  
Author(s):  
Ntebogang Dinah Moroke
Keyword(s):  
United States ◽  
Error Correction ◽  
The United States ◽  
Series Data ◽  
Parameter Estimates ◽  
Household Debt ◽  
Macroeconomic Factors ◽  
Vector Error Correction ◽  
Vector Error ◽  
Long Run

This study applies cointegration and error correction approaches to determine the effect of macroeconomic determinants on household debt in the United States of America. Cointegration analysis provides an effective framework used for estimating and modelling relationships from time series data. Short-run and long-run cointegration models explaining the relationships between the US household debt and related macroeconomic factors are estimated. The data used covers a period of 1990 Q1 to 2013 Q1 and is sourced from the electronic data delivery system of the OECD, USA Federal Housing Finance Agency and the USA Department of the Treasury among others. SAS 9.3 version was used to obtain the results. The sample and variables were meritorious according to KMO and Cronbach’s alpha. Unit root test results provided enough evidence to conclude that the series were stationary after first differencing. Further data analysis was carried out with the first lag chosen by the AIC and SBC. Three cointegrating vectors were identified and were later standardised to correctly provide parameter estimates of the vector error correction model of household debts. The model revealed some short and long-run relationships. Revealed by the model is that 1.5 % of long-run equilibrium was corrected per quarter. The results of the current study are crucial to households and policy makers. Researchers may also refer to these results.

Post-hurricane forest management responses in the southern United States

2009 ◽  
Vol 7 (6) ◽  
pp. 35
Author(s):  
Pete Bettinger, PhD ◽  
Krista L. Merry, MS ◽  
Jeffrey Hepinstall, PhD
Keyword(s):  
United States ◽  
Forest Management ◽  
Forest Health ◽  
Storm Surges ◽  
Weather Conditions ◽  
The United States ◽  
Southern United States ◽  
Service Needs ◽  
Strong Winds ◽  
Social Recovery

Although people living along the southeastern and Gulf coasts of the United States may have limited experience dealing with major hurricane damage, hurricanes are imminent and pose potentially dire consequences to forest resources. In addition to understanding the physical and biological reactions of forests to extreme weather conditions, there are a number of managerial responses that should be considered based on this past experience. This article presents a summary of the more pertinent forest management responses, and where appropriate, highlights situations where these were beneficial to the overall (economic, ecological, social) recovery effort. Management responses address not only the immediate needs for clearing roads and restoring basic service needs, but also the longer-term issues related to timber salvage, reforestation, forest health, and fire danger. The damage from strong winds and storm surges may also result in serious consequences for ecological values. However, challenges and issues related to the restoration of forests and forest-related values may require several years to address. Therefore, the objective of this review article is to provide a summary of the experiences of forest land managers, researchers, and emergency planners who have directly responded to severe storms affecting the southern United States.

scholarly journals What drives endogenous growth in the United States?

2015 ◽  
Vol 15 (1) ◽  
Author(s):  
Dennis Wesselbaum
Keyword(s):  
United States ◽  
Bayesian Estimation ◽  
Endogenous Growth ◽  
The United States ◽  
Learning By Doing ◽  
Technological Innovations ◽  
Parameter Estimates ◽  
Estimation Techniques ◽  
Long Run ◽  
Model Dynamics

AbstractThe cleansing effects of recessions are investigated. We estimate a DSGE model allowing for endogenous growth to be driven by two competing theories. Either learning-by-doing effects or cleansing effects of recessions drive endogenous growth. Using Bayesian estimation techniques we find that reallocation effects in recessions dominate and also non-technological innovations have effects on productivity and, hence, long-run growth. Furthermore, we show that using directly observable TFP in the estimation has sizable effects on parameter estimates, the identification of shocks, and model dynamics.

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