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Quantifying uncertainties and errors in hydrometric observations is critical to improve our ability to predict streamflow. de Oliveira and Vrugt (2022, https://doi.org/10.1029/2022wr032263) expand on an earlier publication (Vrugt et al., 2005, https://doi.org/10.1029/2004wr003059) to describe a difference‐based variance estimation method that is, used to estimate the aleatory observation uncertainty in streamflow records directly from a time series of such data. The method is then applied to hourly data from 500+ catchments across the contiguous United States. This comment outlines our concerns that the assumptions needed to effectively use difference‐based variance estimation methods are not always met by hourly streamflow records. We illustrate our concerns through the use of a specific test case. We argue that more work is needed to quantify the individual sources of errors and uncertainties in hydrometric observations. Key Points: We review the difference‐based variance estimation approach (de Oliveira & Vrugt, 2022, https://doi.org/10.1029/2022wr032263) to estimate uncertainty in streamflow recordsWe outline our concerns that this method is not always applicable for streamflow records at hourly time stepsMore work is required to explicitly quantify individual error sources in hydrometric monitoring programs [ABSTRACT FROM AUTHOR]

This article will address predictors of success for online students. A survey questionnaire was used to gather data concerning the social and educational levels of readiness of online students at a four-year private university in the Midwestern United States. Of the 4,050 potential participants, 250 (6.23%) responded to the survey. Stepwise regression revealed two models for predicting student performance on two key dependent variables in this study. The first model sought to predict student success based on their self-reported views on whether they felt successful in their online courses. This model revealed 11 survey questions that were significant predictors of students self-reported success scores, b = .382, t (17.737) = 5.399, p < .001. The eleven questions in the model also explained a significant proportion of variance in the self-reported success scores, R² = .472, F (1, 171) = 29.15, p < .001. The second model focused on the dependent variable of self-reported grade point average (GPA) of students. Of the questions asked in the survey the second model showed eight variables that were statistically significant predictors of student GPA, b = -.397, t (110.066) = -5.767, p < .001. These eight survey questions explain a significant portion of the variance for students' self-reported grade point averages, R² = .359, F (1, 178) = 33.261, p < .001. These finding shed light on the importance of student perspective concerning persistence and success in online education. Limitations of the study and recommendations for future research were provided. [ABSTRACT FROM AUTHOR]

This paper presents an empirical microstructure model of bid and ask quotes that features discreteness, random costs of market making, and ARCH volatility effects. Applied to intraday quotes at 15-minute intervals for Alcoa (a randomly chosen Dow stock), the results show that quote exposure costs contain stochastic components that are persistent and large relative to the deterministic intraday "U" components. Analysis of the filtered estimates of the system suggest that bid and ask costs contain common components, and that these costs reflect risk as proxied by ARCH variance forecasts. [ABSTRACT FROM AUTHOR]

The article focuses on a dynamic analysis of the impact fiscal policy has on the money supply. It states that assumptions about the U.S. Federal Reserve's behavior influences variances in the magnitude of dynamic multipliers. It mentions that failures in modeling the Federal Reserve's response to fiscal policy can result in an underestimation of the effect that fiscal actions have on money supply, and provides empirical support to the argument that if policymakers react systematically to the economy's state, the model multipliers will be biased unless this reaction is explicitly accounted for in the model.

The article offers information on a court case between Antioch Community Church v. Board of Zoning Adjustment of City of Kansas City in which church seeking a zoning variance for an updated sign. The topics addressed include details on the land use planning, in which there are generally two broad categories of variances comprising use variances and non-use variances.

This paper examines the return predictability of the US stock market using portfolios sorted by size, book-to-market ratio and industry. We use novel panel variance ratio tests, based on the wild bootstrap proposed in this paper, which exhibit desirable size and power properties in small samples. We have found evidence that stock returns have been highly predictable from 1964 to 1996, except for a period leading to the 1987 crash and its aftermath. After 1997, stock returns have been unpredictable overall. At a disaggregated level, we find evidence that large-cap portfolios have been priced more efficiently than small- or medium-cap portfolios; and that the stock returns from high-tech industries are far less predictable than those from non-high-tech industries. [ABSTRACT FROM AUTHOR]

We explore the behavior of total monthly returns of U.S. Treasury bills from January 1926 to December 2011. We examine three types of month effects: if the mean of T-bills total monthly returns of the data set, and of a given month were significantly different from zero; if the mean of T-bills total monthly returns of a given month was different from the mean of the other eleven months stacked; and if the variance of the T-bills total monthly returns for a given month was different from the variance of the other eleven months stacked. The mean of T-bills total monthly returns (0.294%) for the data set as well as the mean of all the months were significantly greater than zero. No month effect was detected either in terms of mean or in terms of variance. When we slice the data into three sub-periods, we found results similar to what we found for the entire data set. The non-existence of significant differences in the means or the volatilities of the returns of a month compared to the other eleven months stacked shows that the Tbills market is largely efficient. This is contrary to what we found with similar studies on monthly returns of long-term Treasury and corporate bonds. The mean of T-bills total monthly returns during the Republican presidencies (0.372%) was higher than during the Democratic presidencies (0.215%). Compared to the other eleven months stacked, the variance of the returns of December during Republican presidencies was lower whereas it was higher during Democratic presidencies. [ABSTRACT FROM AUTHOR]

We investigate the managerial incentives and debt cost effects associated with budget-to-actual variance disclosures required by the GASB No. 34 reporting model. Empirically, we document associations between variances and municipal bond ratings in a sample of large U.S. cities over the period 2003-2006. We find a disproportionate share of favorable variances for revenues, expenditures, and the net (i.e., surplus/deficit). Further, we show that revenue variances in either direction are associated with lower bond ratings, i.e., precision is important in predicting revenues. In contrast, favorable expenditure variances are associated with higher bond ratings, i.e., imprecision may be tolerated if the variance is favorable. These associations exist despite indirect evidence of managerial incentives to create budgetary slack for both revenues and expenditures. The findings suggest that these disclosures required in the GASB No. 34 financial reporting model indicate factors that influence municipal debt costs. [ABSTRACT FROM AUTHOR]

The article discusses the indeterminacy regarding variance calculations and analyzes the U.S. Supreme Courts decision in Gall v. United States that that the federal appeals courts may not presume that a sentence falling outside the range recommended by the Federal Sentencing Guidelines is unreasonable. It describes the background of the U.S. Sentencing Guidelines and the emerging relationship between district and appellate court sentencing power.

We present a surprising though obvious result that seems to have been unnoticed until now. In particular, we demonstrate the equivalence of two well-known problems—the optimal allocation of the fixed overall sample sizenamongLstrata under stratified random sampling and the optimal allocation of theH= 435 seats among the 50 states for apportionment of the U.S. House of Representatives following each decennial census. In spite of the strong similarity manifest in the statements of the two problems, they have not been linked and they have well-known but different solutions; one solution is not explicitly exact (Neyman allocation), and the other (equal proportions) is exact. We give explicit exact solutions for both and note that the solutions are equivalent. In fact, we conclude by showing that both problems are special cases of a general problem. The result is significant for stratified random sampling in that it explicitly shows how to minimize sampling errorwhen estimating a totalTYwhile keeping the final overall sample size fixed atn; this is usually not the case in practice with Neyman allocation where the resulting final overall sample size might be nearn+Lafter rounding. An example reveals that controlled rounding with Neyman allocation does not always lead to the optimum allocation, that is, an allocation that minimizes variance. [ABSTRACT FROM PUBLISHER]

This paper estimates the sampling error variances of gridded monthly U.S. Historical Climatology Network, version 2 (USHCN V2), time-of-observation-biases (TOB)-adjusted data. The analysis of mean surface air temperature (SAT) assesses uncertainties, trends, and the rankings of the hottest and coldest years for the contiguous United States in the period of 1895-2008. Data from the USHCN stations are aggregated onto a 2.5° × 3.5° latitude-longitude grid by an arithmetic mean of the stations inside a grid box. The sampling error variances of the gridded monthly data are estimated for every month and every grid box with data. The gridded data and their sampling error variances are used to calculate the contiguous U.S. averages and their trends and associated uncertainties. The sampling error variances are smaller (mostly less than 0.2°C2) over the eastern United States, where the station density is greater and larger (with values of 1.3°C2 for some grid boxes in the earlier period) over mountain and coastal areas. In the period of 1895-2008, every month from January to December has a positive linear trend. February has the largest trend of 0.162°C (10 yr)−1, and September has the smallest trend at 0.020°C (10 yr)−1. The three hottest (coldest) years measured by the mean SAT over the United States were ranked as 1998, 2006, and 1934 (1917, 1895, and 1912). [ABSTRACT FROM AUTHOR]

This study examined the asset ownership of Asian immigrants using a nationally representative sample of newly legalized immigrants (New Immigrant Survey). Findings revealed that ownership of a business or farm, financial assets, and home ownership were associated with socioeconomic, demographic, and acculturation variables. Family income, education, English fluency, and length of stay were significant in all types of asset ownership. Variances in asset ownership by ethnic groups exist. Asian Indians and Koreans had higher levels of business asset ownership. Korean, and Filipino immigrants were also more likely to be homeowners. Asian Indian and Chinese immigrants were more likely to own financial assets. Vietnamese lagged in business or farm and financial asset ownership. Findings provided insights into the investment decisions of new Asian immigrants for financial educators, researchers, and policymakers. [ABSTRACT FROM AUTHOR]

This article outlines a simple regression-based method to decompose the variance of an aggregate time series into the variance of its components, which is then applied to measure the relative contributions of productivity, hours per worker and employment to cyclical output growth across a panel of countries. Measured productivity contributes more to the cycle in Europe and Japan than in the United States. Employment contributes the largest proportion of the cycle in Europe and the United States (but not Japan), which is inconsistent with the idea that higher levels of employment protection in Europe dampen cyclical employment fluctuations. [ABSTRACT FROM AUTHOR]

Despite significant policy efforts to encourage Americans to save for retirement, the U.S. retirement savings rates have declined for more than two decades. Current policies and programs are largely driven by three implicit theories of why people do and do not save: trait theory, life cycle, and education. The authors' purpose is not to identify a singular best theory but rather to demonstrate the need to expand the theories used to address the retirement savings problem. Toward that end, they empirically examine each traditional theory and simultaneously explore the additional power of complementary theories: future-self theory and imagery. The results show that variables grounded in trait theory, life cycle, and education are significantly related to retirement planning. Moreover, people who reported greater and more vivid imagery of a positive future retired self had engaged in more retirement preparation, accounting for a significant amount of variance beyond the traditional theories. [ABSTRACT FROM AUTHOR]

Benefit-cost models are frequently used to inform environmental policy and management decisions. However, they typically omit a random or pure error which biases downward any estimated forecast variance. Ex-ante benefit-cost analyses create a particular problem because there are no historically observed values of the dependent variable, such as net present social value, on which to construct a historically based variance as is the usual statistical approach. To correct this omission, an estimator for the random error variance in this situation is developed based on analysis of variance measures and the coefficient of determination, R². A larger variance may affect decision-maker's choices if they are risk averse, consider confidence intervals, exceedance probabilities, or other measures related to the variance. When applied to a model of the net benefits of the Clean Air Act, although the probability of large net benefits increases, the probability that the net present value is negative also increases from 0.2 to 4.5%. A framework is also provided to assist in determining when a variance estimate would be better, in a utility sense, than using the current default of a zero error variance. [ABSTRACT FROM AUTHOR]

ObjectiveTo determine the number of 24 h dietary recalls required to adequately estimate nutrient intake in overweight and obese adults using the US Department of Agriculture's (USDA) automated multiple-pass method (AMPM). In addition, the study quantified sources of variation in dietary intake, such as day of the week, season, sequence of diet interviews (training effect), diet interviewer, body weight and within- and between-subject variances in the intake of selected nutrients.DesignAdults having a BMI of ≥ 28 but <38 kg/m2 were included in the study. The USDA's AMPM was used to obtain 24 h dietary recalls every 10 d for 6 months. Dietary intake data were analysed to adequately estimate the number of 24 h recalls necessary to assess nutrient intake. Variance component estimates were made by using a mixed-model procedure.SettingThe greater Washington, DC, metropolitan area.SubjectsAdults (34 men and 39 women) aged 35–65 years.ResultsOverweight and obese adults completed fourteen 24 h dietary recalls. Utilizing within- and between-subject variances requires 5–10 and 12–15 d of 24 h dietary recalls in men and women, respectively, to estimate energy and macronutrient intakes in a 6-month period. Within- and between-subject variances were the major contributors to variance in nutrient intakes. Day of the week, season, sequence, diet interviewer and body weight had little impact on variance.ConclusionsThis information is valuable for researchers planning to conduct studies on free-living individuals that include the collection of dietary intake data. [ABSTRACT FROM AUTHOR]

This review covers recent research on breakup distress in university students using the Breakup Distress Scale adapted from the Inventory of Complicated Grief. In the first study, 37% of the variance in Breakup Distress Scale scores was explained by depression, feelings of betrayal, having less time since the breakup and higher relationship ratings. In a second study, intrusive thoughts contributed to 28% of the variance. Depression and sleep disturbances were also related to breakup distress in this sample. Other negative emotions and behaviors included anxiety, anger, disorganized behavior and inferior academic performance. Studies on reasons for breakups revealed that insecurity and loss of intimacy were the most significant problems in those experiencing breakup distress. Although female students typically reported greater breakup distress, the studies are limited in their generalizability because they sampled primarily Hispanic female psychology students. Nonetheless, the data highlight the negative effects of breakup distress for university students. [ABSTRACT FROM AUTHOR]

We surveyed business students in the United States (n = 256) and Chile (n = 310) to compare three theories of pro-environmental behavior.We examined Ajzen and Fishbein’s theory of reasoned action, Schawartz’s norm activation theory, and the values-beliefs-norms theory created by Stern, Dietz, Abel, Guagnano, and Kalof. We produced reliable measures for both samples. Each theory explained a significant amount of the variance in behavioral intention, although no theory clearly dominated for either the United States or Chile. However, among the variables included among these theories, the norms variable consistently produced the strongest relationship with behavioral intention. We discuss avenues of future research focusing on norms and more parsimonious combinations of the variables across these three theories. [ABSTRACT FROM AUTHOR]

The current study takes a novel approach to studying the correlates of subjective well-being. Unlike previous studies, which typically examine group-level well-being at the state or national level, we analyzed correlates of well-being at the county level within the United States. Using nationally representative data, we found that reliable variance in well-being exists across counties. Furthermore, this variance was associated with a number of objective factors, including income, population density, health and education. Continued study of these factors at the regional level may have important implications for developing community programs and public policy. [ABSTRACT FROM AUTHOR]

Among the three timberland return drivers (biological growth, timber price, and land price), timber price remains the most unpredictable. It affects not only periodic dividends from timber sales but also timber production strategies embedded in timberland management. Using various time series techniques, this study aimed to model and forecast real pine sawtimber stumpage prices in 12 southern timber regions in the United States. Under the discrete-time framework, the univariate autoregressive integrated moving average model was established as a benchmark, whereas other multivariate time series methods were applied in comparison. Under the continuous-time framework, both the geometric Brownian motion and the Ornstein–Uhlenbeck process were fitted. The results revealed that (i) the vector autoregressive model forecasted more accurately in the 1-year period by the mean absolute percentage error criterion, (ii) seven out of the 12 southern timber regions played dominant roles in the long-run equilibrium, and (iii) conditional variances and covariances from the bivariate generalized autoregressive conditional heteroscedasticity model well captured market risks. [ABSTRACT FROM AUTHOR]

Context: The concept of culture and its relationship to athletic training beliefs and practices is virtually unexplored. The changing demographics of the United States and the injuries and illnesses of people from diverse backgrounds have challenged health care professionals to provide culturally competent care. Objective: To assess the cultural competence levels of certified athletic trainers (ATs) in their delivery of health care services and to examine the relationship between cultural competence and sex, race/ethnicity, years of athletic training experience, and National Athletic Trainers' Association (NATA) district. Design: Cross-sectional survey. Setting: Certified member database of the NATA. Patients or Other Participants: Of the 13 568 ATs contacted, 3102 (age = 35.3 ± 9.41 years, experience = 11.2 ± 9.87 years) responded. Data Collection and Analysis: Participants completed the Cultural Competence Assessment (CCA) and its 2 subscales, Cultural Awareness and Sensitivity (CAS) and Cultural Competence Behavior (CCB), which have Cronbach alphas ranging from 0.89 to 0.92. A separate univariate analysis of variance was conducted on each of the independent variables (sex, race/ethnicity, years of experience, district) to determine cultural competence. Results: The ATs' self-reported scores were higher than their CCA scores. Results revealed that sex (F1,2929 = 18.63, P = .001) and race/ethnicity (F1,2925 = 6.76, P = .01) were indicators of cultural competence levels. However, we found no differences for years of experience (F1,2932 = 2.34, P = .11) or NATA district (F1,2895 = 1.09, P = .36) and cultural competence levels. Conclusions: Our findings provide a baseline for level of cultural competence among ATs. Educators and employers can use these results to help develop diversity training education for ATs and athletic training students. The ATs can use their knowledge to provide culturally competent care to athletes and patients and promote a more holistic approach to sports medicine. [ABSTRACT FROM AUTHOR]

We investigate households' portfolio choice using a microeconometric approach derived from mean–variance optimization. We assume that households have heterogeneous expectations on the distribution of excess returns and that they cannot take short positions in risky assets. Assuming two such assets, we derive an explicit solution of the model characterized by four possible portfolio regimes, which are analyzed using two structural probit and tobit specifications with three latent state variables. Both specifications are estimated by weighted maximum likelihood on a cross-section of US households drawn from the 2004 SCF. The tobit specification is simulated in order to evaluate the regressors' effects on regime probabilities and asset demands. We also assess to what extent the predicted state variables are consistent with the self-reported expected returns and risk aversion elicited from the SCF questionnaire. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: The goal of this paper is to examine whether the volatility of the growth in the US oil stocks has changed overtime, and if it has then whether or not this change is real. We find that the growth in volatility of oil stocks has declined overtime. We conduct a Monte Carlo simulation exercise to investigate whether this decline is real or an artefact of the growth definition. Our findings support the fact that the decline in growth volatility of oil stocks is an artefact of the growth definition. This is because a data generating process having a unit root with drift has a tendency to grow and thereby pulls the variance of growth down with time. [Copyright &y& Elsevier]

The article focuses on the revision made to certification requirement for the U.S. Department of Defense (DoD)'s program execution. It mentions that the key documents such as the DoD Instruction (DoDI) have been revised to create a mandatory early decision points as well as analysis such as the material development decision. It then illustrates that in incorporating the tools and techniques, adding variable idling time which reduces net setup variance achieves lower waiting time in the setup process.

Hydrologic model calibration is usually a central element of streamflow forecasting based on the ensemble streamflow prediction (ESP) method. Evaluation measures of forecast errors such as root-mean-square error (RMSE) are heavily influenced by bias, which in turn is readily reduced by calibration. On the other hand, bias can also be reduced by postprocessing (e.g., “training” bias correction schemes based on retrospective simulation error statistics). This observation invites the question: How much is forecast error reduced by calibration, beyond what can be accomplished by postprocessing to remove bias? The authors address this question through retrospective evaluation of forecast errors at eight streamflow forecast locations distributed across the western United States. Forecast periods of length ranging from 1 to 6 months are investigated, for forecasts initiated from 1 December to 1 June, which span the period when most runoff occurs from snowmelt-dominated western U.S. rivers. ESP forecast errors are evaluated both for uncalibrated forecasts to which a percentile mapping bias correction approach is applied, and for forecasts from an objectively calibrated model without explicit bias correction. Using the coefficient of prediction (Cp), which essentially is a measure of the fraction of variance explained by the forecast, the authors find that the reduction in forecast error as measured by Cp that is achieved by bias correction alone is nearly as great as that resulting from hydrologic model calibration. [ABSTRACT FROM AUTHOR]

The article focuses on the Effects-Based Operations (EBO) of the Department of Defense (DOD). It examines the effectivity of the suggested EBO course of action starting with a functional capability definition of effect to embody attributes including consistency with the Joint 5-0 Publication. Significant inherent reliability and unreliability representation using mean and variance of each action and system component step to account for the probabilistic outcomes in EBO planning are also given.

This article analyses the seasonality in the monthly consumer price index (CPI) over the period January 1913 to December 2003. We examine three types of month effects: if the mean of monthly CPI changes of the entire data set, and of a given month were significantly different from zero; if the mean of monthly CPI changes of a given month was different from the mean of the other months; and if the variance of the monthly CPI changes for a given month was different from the variance of the other months. The mean of monthly CPI changes for the entire data set (0.27%) was found to be significantly greater than zero. The means of monthly changes show a downward trend from September to December. When the data are sliced into three sub-periods, we find an increasing trend in the means and medians of monthly changes but a decreasing trend in the SDs of the monthly changes. The mean of monthly CPI changes during the republican presidencies (0.15%) was significantly lower than during the democratic presidencies (0.38%). [ABSTRACT FROM AUTHOR]

This paper examines the degree to which government administrators incorporate prior year spending variances into current year budgets. Government administrators have incentives to increase their budgets, and constraints on government spending are weaker than those found in the private sector. Therefore, we expect budget increases associated with prior year government overspending (actual exceeds budget) to be larger than decreases associated with underspending of the same amount. This differential response is called ratcheting. We examine budgets for 1,034 Texas school districts (1995 through 2002), and find budget ratcheting in operating expenditures and the subcategories of instructional and non-instructional expenditures. Ratcheting is most pronounced for non-instructional expenditures. We also find that budget ratcheting is more pronounced when controls on government spending are likely to be weaker. Specifically, budget ratcheting is more pronounced for school districts that operate in a less competitive environment and for districts that have less voter influence. [ABSTRACT FROM AUTHOR]

We present two models for the short-term prediction of the number of deaths arising from common cancers in the United States. The first is a local linear model, in which the slope of the segment joining the number of deaths for any two consecutive time period is assumed to be random with a nonparametric distribution, which has a Dirichlet process prior. For slightly longer prediction periods, we present a local quadratic model. This extension of the local linear model includes an additional "acceleration" term that allows it to quickly adjust to sudden changes in the time series. The proposed models can be used to obtain the predictive distributions of the future number of deaths. as well their meals and variances through Markov chain Monte Carlo techniques. We illustrate our methods by runs on data from selected cancer sites. [ABSTRACT FROM AUTHOR]

In this study, we compared the depressive symptoms reported by Mexican American elders who scored higher and lower on a linguistic acculturation scale. Prevalence, equality of covariance matrices, equality of error variances, and factor structures were examined for the 20 items included in the Center for Epidemiologic Studies Depression (CES-D) Scale. The sample consisted of 3,050 community-dwelling Mexican Americans from five states. Significant differences were found on all parameters, indicating that level of acculturation is associated with pervasive differences in the way items are endorsed on the most commonly used inventory of depressive symptoms. Results add to literature suggesting that there may not be a universal structure to symptoms. Higher or lower scores may have different implications for people representing different cultures and/or stages of acculturation, something that both researchers and clinicians should be sensitive to when interpreting results of screening tests. [ABSTRACT FROM AUTHOR]

Abstract: In IQ and the Wealth of Nations (2002), Lynn and Vanhanen estimate the mean IQs of 185 nations and demonstrate that national IQs strongly correlate with the macroeconomic performance of the nations, explaining about half of the variance in GDP per capita. I seek to replicate Lynn and Vanhanen''s results across states within the United States. I first estimate “state IQs” from the SAT data, and show that the state IQs correlate moderately with the economic performance of the states, explaining about a quarter of the variance in GSP (gross state product) per capita. [Copyright &y& Elsevier]

We propose a simple model of trooper behavior to design empirical tests for whether troopers of different races are monolithic in their search behavior, and whether they exhibit relative racial prejudice in motor vehicle searches. Our test of relative racial prejudice provides a partial solution to the well-known inframarginality and omitted-variables problems associated with outcome tests. When applied to a unique data set from Florida, our tests soundly reject the hypothesis that troopers of different races are monolithic in their search behavior, but the tests fail to reject the hypothesis that troopers of different races do not exhibit relative racial prejudice. [ABSTRACT FROM AUTHOR]

A multivariate regime-switching model for monetary policy is confronted with U.S. data. The best fit allows time variation in disturbance variances only. With coefficients allowed to change, the best fit is with change only in the monetary policy rule and there are three estimated regimes corresponding roughly to periods when most observers believe that monetary policy actually differed. But the differences among regimes are not large enough to account for the rise, then decline, in inflation of the 1970s and 1980s. Our estimates imply monetary targeting was central in the early 1980s, but also important sporadically in the 1970s. [ABSTRACT FROM AUTHOR]

In this paper quantile regression is used to explore the relation of current and lagged productivity levels of U.S. manufacturing industries. Productivity is calculated in the form of total factor productivity by a non-parametric approach. Bootstrap-based confidence intervals and specification tests are reported. Key findings are that a first-order Markov process provides a valid description of productivity transitions and that persistence is larger in the range of higher productivity levels. This is reinforced by the widespread insignificance of additional conditioning variables. A notable exception is the variability of the growth path which increases explanatory power substantially. [ABSTRACT FROM AUTHOR]

Students who are new to statistics and its role in modern finance have a hard time making the connection between variance and risk. To link these, we developed a classroom simulation in which groups of students roll dice that simulate the success of three investments. The simulated investments behave quite differently: one remains almost constant, another drifts slowly upward, and the third climbs to extremes or plummets. As the simulation proceeds, some groups have great success with this last investment-they become the "Warren Buffetts" of the class, accumulating far greater wealth than their classmates. For most groups, however, this last investment leads to ruin because of its volatility, the variance in its returns. The marked difference in outcomes surprises students who discover how hard it is to separate luck from skill. The simulation also demonstrates how portfolios, weighted combinations of investments, reduce the variance. Students discover that a mixture of two poor investments emerges as a surprising performer. After this experience, our students immediately associate financial volatility with variance. This lesson also introduces students to the history of the stock market in the U.S. We calibrated the returns on two simulated investments to mimic returns on U.S. Treasury Bills and stocks. [ABSTRACT FROM AUTHOR]

The size distribution and growth rate dynamics of U.S. companies have been extensively studied by many authors. In this paper, using the COMPUSTAT database, we extend the analysis to disaggregated data, studying 15 sectors of the U.S. manufacturing industry. The sectoral investigation reveals the presence of general statistical properties that can be considered valid across all the studied sectors. In particular, the probability density of firms growth rates invariably displays a characteristic tent shape and the relation between the size of a firm and the variance of its rates of growth is characterized, in different sectors, by very similar scaling relations. The presence of characteristics that are robust and sectoral invariant hints at the existence of generic statistical properties shaping the dynamic of firms across the whole industry. [ABSTRACT FROM AUTHOR]

The capture-recapture approach to estimating the size of a population is a well-studied area of statistics. The number of distinct individuals, NA and NB, on each of two lists, A and B, and the number common to both lists, NAB, are used to form an estimate of the binomial probability of being on one of the lists, which then allows an estimate to be made of the size of the population. Critical to the method is an accurate count of NAB. We consider situations in which this count is not available. Such problems arise in a variety of behavioural health contexts in which the need for protection of privacy may prevent sharing identifying information, so it is not possible to specifically match an individual who appears on one list with an individual on the other. Suppose that the birth dates and/or other demographics of individuals on each list are known. We introduce two methods for estimating the duplication rates and the size of the population. Conditioning on the set β of birth dates of those on list B, NA and NB, the maximum likelihood estimators (MLEs) and their variance are derived. The MLEs are based on the proportion of individuals on list A whose birth dates fall in β. This approach is particularly useful if list B itself contains duplicates. The second model utilizes the full sample distribution of the birth dates. We generalize this approach to accommodate multiple demographic characteristics. The approaches are applied to the problem of estimating duplication rates and the population size of veterans who have mental illness in Kings County, NY. The data are lists of those receiving service from the Veterans Administration system and from providers funded or certified by the New York State Office of Mental Health. Copyright © 2003 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The paper advances the log-generalized gamma distribution as a suitable generator of conditional skewness. Based on the NYSE composite daily returns an asMA-asQGARCH model along with skewness dynamics is estimated. The results indicate a skewness that varies between sizeable negative skewness and almost symmetry. The conditional variance and skewness measures are negatively correlated. [ABSTRACT FROM AUTHOR]

This study explored the effects of student levels of trait verbal aggressiveness (VA) and self-esteem on student perceptions of instructor verbal aggressiveness in the college classroom. Participants included 228 undergraduate students who completed a series of instruments measuring self-reported levels of VA and self-esteem, as well as instructor levels of VA in the classroom. Results indicated that students who reported moderate to high levels of trait VA rated their instructors as being more verbally aggressive than those students who reported low levels of trait VA. Likewise, students who reported low to moderate levels of self-esteem rated their instructors as being more verbally aggressive than those students who reported high levels of self-esteem. When combined, student VA and self-esteem accounted for 7% of the shared variance in student perceptions of instructor VA. [ABSTRACT FROM AUTHOR]

The extent of organizational innovation with information technology, an important construct in the IT innovation literature, has been measured in many different ways. Some measures have a narrow focus while others aggregate innovative behaviors across a set of innovations or stages in the assimilation lifecycle. There appear to be some significant tradeoffs involving aggregation: more aggregated measures can be more robust and generalizable and can promote stronger predictive validity, while less aggregated measures allow more context-specific investigations and can preserve clearer theoretical interpretations. This article begins with a conceptual analysis that identifies the circumstances when these tradeoffs are most likely to favor aggregated measures. It is found that aggregation should be favorable when: (1) the researcher's interest is in general innovation or a model that generalizes to a class of innovations, (2) antecedents have effects in the same direction in all assimilation stages, (3) characteristics of organizations can be treated as constant across the innovations in the study, (4) characteristics of innovations can not be treated as constant across organizations in the study, (5) the set of innovations being aggregated includes substitutes or moderate complements, and (6) sources of noise in the measurement of innovation may be present. The article then presents an empirical study using data on the adoption of software process technologies by 608 U.S. based corporations. This study--which had circumstances quite favorable to aggregation--found that aggregating across three innovations within a technology class more than doubled the variance explained compared to single innovation models. Aggregating across assimilation stages also had a slight positive effect on predictive validity. Taken together, these results provide initial confirmation of the conclusions from the conceptual analysis regarding the circumstances favoring aggregation. [ABSTRACT FROM AUTHOR]

Recent studies suggest that the term premia within the US Term Structure of Interest Rates may be adequately characterized as univariate GARCH(1, 1)-M processes, with highly persistent or even potentially explosive conditional variances. Tzavalis and Wickens (Economics Letters, 49, 1995) using data over the period 1970-1986 argue that such findings may be the result of the failure of the GARCH-M model to allow for the 1979-82 change in US monetary policy. Using an alternative approach, the results in this paper suggest that the conclusion of Tzavalis and Wickens may not be independent of the sample period considered. However the GARCH-M model provides implausible estimates of the term premia when estimated over the full sample period. [ABSTRACT FROM AUTHOR]

Demographic forecasting techniques fail with post-transition populations dominated by fluctuating fertility; time series analysis of fertility can improve the forecasts. This article develops the optimal forecast and its variance for births to an age-structured population subject to serially correlated random fertility. The white noise, first-order auto- regressive, second-order autoregressive and random walk fertility specifications are analyzed, each leading to different forecasts and very different variances, as shown by illustrative applications to U.S. data, 1917-1972. [ABSTRACT FROM AUTHOR]

Presents information on the follicle and seed morphology of 94 Hakea species in southwestern Australia and their relationship with serotiny. Ability to retain mature seeds on the plant for an extended period (serotiny) is characteristic of many species inhabiting fire-prone environments in Australia, South Africa and the U.S.; Relationship of follicle size and wall thickness with the ability of follicles to protect seeds from external heat; Analysis of data collected for the study using one-way analysis of variance with residual plots of each analysis examined for homogeneity of variances.

We consider the time series behavior of the U.S. real interest rate from 1961 to 1986, using the methodology of Hamilton (1989), by allowing three possible regimes affecting both the mean and variance. The results suggest that the ex-post real interest rate is essentially random with means and variances that are different for the periods 1961-1973, 1973-1980 and 1980- 1986. The inflation rate series also shows interesting shifts in both mean and variance Series for the ex-ante real interest rate and expected inflation are constructed. Finally, we make clear how our results can explain some recent findings in the literature. [ABSTRACT FROM AUTHOR]

Exports from Britain to the United States from 1900 to 1940 are examined to ascertain the effect of exchange-rate volatility on the volume of trade. In addition to using a rolling standard deviation measure of exchange rate uncertainty, the conditional variance of the exchange-rate series modelled as a generalized autoregressive conditional heteroskedastic (GARCH) process is used to generate an alternative measure of exchange-rate uncertainty. The results of estimation using the two measures of exchange-rate volatility suggest that increases in the volatility of the real exchange rate reduce the volume of trade. [ABSTRACT FROM AUTHOR]

Abstract--This study examines relative wage variability across industries between 1860 and 1983. The variance across industries in wage growth was at least four times larger before 1948 than afterward. Except for smaller year-to-year variability in output growth across industries after 1948, the macroeconomic factors examined cannot account for this increased rigidity of relative wages. Increases in average establishment size and improved communication of wage trends are probably partially responsible for the observed increase in relative wage rigidity. No single macroeconomic model was consistent with the year-to-year fluctuations in relative wage rigidity in every historical period examined. [ABSTRACT FROM AUTHOR]

The purpose of this article is to ascertain the extent to which deterrence, environment, and culture can be considered responsible for the observed variance in the propensity for criminal behavior across countries. It is based on time-series observations on robberies from 1955 to 1971 for three countries, England, Japan and the U.S. as represented by California. The differential impacts on the per-capita robbery rate of the certainty and severity of punishment and of economic and demographic characteristics are estimated. A single equation approach, as pursued in this article, can provide unambiguous evidence on the deterrence issue only if the level of deterrence is unaffected by variations in the level of crime. Two arguments for this feedback from crime to enforcement have been suggested in the literature, one technical and the other behavioral. This article, it is hoped, has served to demonstrate that careful examination of comparative criminal statistics is both possible and fruitful. It is surely true that more would be learned from an expanded analysis in both the cross-sectional and temporal dimension, but only recently have more countries been collecting data that permit comparison.

This article provides empirical tests of the risk differences between two types of ownership structure in the property-liability insurance industry. Empirical evidence is provided that suggests stock insurers have more risk than mutuals where the risk inherent in future cash flows is proxied by the variance of the loss ratio. Further evidence suggests that stock insurers write relatively more business than do mutuals in lines and states having higher risk. [ABSTRACT FROM AUTHOR]