On the validity of MAPE as a measure of population forecast accuracy

The mean absolute percent error (MAPE) is the summary measure most often used for evaluating the accuracy of population forecasts. While MAPE has many desirable criteria, we argue from both normative and relative standpoints that the widespread practice of exclusively using it for evaluating population forecasts should be changed. Normatively, we argue that MAPE does not meet the criterion of validity because as a summary measure it overstates the error found in a population forecast. We base this argument on logical grounds and support it empirically, using a sample of population forecasts for counties. From a relative standpoint, we examine two alternatives to MAPE, both sharing with it, the important conceptual feature of using most of the information about error. These alternatives are symmetrical MAPE (SMAPE) and a class of measures known as M-estimators. The empirical evaluation suggests M-estimators do not overstate forecast error as much as either MAPE or SMAPE and are, therefore, more valid measures of accuracy. We consequently recommend incorporating M-estimators into the evaluation toolkit. Because M-estimators do not meet the desired criterion of interpretative ease as well as MAPE, we also suggest another approach that focuses on nonlinear transformations of the error distribution.     

SOCIAL STRESS AND MENTAL HEALTH IN THE SOUTHERN BLACK BELT

Black Belt counties in the southeastern United States are among the very poorest of all. Much of the economic, political, and social landscape of the region still echoes the problems of its antebellum past. Black white relations in the region are still characterized by antagonisms at all levels of social life. In this study, I examine the impact of social and material conditions of the Black Belt on mental health. I use data from a sample of Black and White workers in North Carolina, a state that re ects many of the racial dynamics found across the Southeast. Findings show that racial patterns in psychological distress are associated with the strength of political and economic elites in the Black Belt who have historically maintained power through racial subjugation. In conclusion, I discuss the theoretical implications of the findings.     

Narrative Hesitation in The Gambler

My article contends that Dostoevsky’s short novel, The Gambler, is marked by a fundamental conflict of temporalities. While the novel seems to embrace bourgeois optimism and the hopeful narrative temporality that serves as its most resourceful literary embodiment, it also seems to adhere to a strikingly anti-teleological and circular narrative structure. This affirmation and denial of temporality as linear, purposive movement is the appropriate narrative emblem of the peculiar world of Roulettenburg and its inhabitants, a world where beginning and end continually risk equivalence and where the parameters of structure have therefore begun to dissolve. What emerges is an acceptance of inevitable boredom, of permanent failure to resolve conflict, that is both constricting and liberating. As an artistic principle of form, this failure declares a “poetics” of hesitation whose temporal dimensions brilliantly reflect the fundamentally ambivalent eros of the gambler, the latter’s inability to accept or escape from a debilitating presentness. In creating this kind of narrative conflict, Dostoevsky reverses the characteristic romantic obsession with the allure of pregnant immediacy that is an illusion of god-like vision to which only a most ungod-like being could succumb.     

Substrate reinforcement and dialectal differences in Melanesian Pidgin

Stabilization of a new contact language involves a process of levelling, or the reduction of variants. One of the factors influencing which grammatical variants are retained in the process is substrate reinforcement – the existence in the substrate languages of a congruent structure with a similar function. This article illustrates substrate reinforcement in the development of the three current dialects of Melanesian Pidgin. First, evidence of earlier variability is presented and the sociolinguistic conditions that later led to greater stability are described. Second, five grammatical features that differentiate the dialects are examined. For each feature, it is shown first that at least two variants were previously in use. Then evidence is presented illustrating correspondence between the particular variant retained in the dialect and a feature of the substrate languages of that geographic area. Differing substrates reinforced different variants, and this accounts for these dialectal differences.     

“Scissors,Please”: The Practical Accomplishment of Surgical Work in the Operating Theater

The focus of this article is on professional activity in the operating theater. We explore how surgeons and nurses organize their activities, how social interaction is used to help structure and define situations, and how differentials in knowledge are constructed and oriented to. We utilize some ideas and concepts from symbolic interactionism, ethnomethodology, and conversation analysis to analyze small clips of audio‐ and video‐recorded interaction. Focusing on how surgeons and nurses request, provide, and apply surgical instruments, the analysis shows how surgical work is accomplished through talk and bodily conduct. We conclude that, examined in detail, the social interaction between surgeons and nurses is analytically inseparable from the “technical” demands of their work.     

Piet Draghoender's Lament

The main purpose of the paper is to provide a context for “Piet Draghoender's Lament, “a most remarkable piece of oral literature composed spontaneously by a 76‐year‐old illiterate Coloured farmer facing eviction from his birthplace. His feelings and attitudes are representative of the entire Kat River community.

The paper explains the claim of the Draghoenders to their land in terms of the concept of “bloedgrond”: the blood which they inherited and the blood which they spilled to “free” the ground and to make it their own. It also analyses the agonised conflict in Draghoender's mind between his innate resentment and his religious conviction that it is his duty to submit to the will of God. The paper concludes by recounting the subsequent history of the Draghoender family, which illustrates the way in which their religious beliefs undermined their ability to fight for their rights.     

Heart Disease Risk Perception in College Men and Women

Abstract

The authors sought to assess the perception of risks for coronary heart disease (CHD) in college men and women. They surveyed 470 undergraduates from 2 major 4-year institutions who completed a questionnaire that measured perceived risks for heart disease. Sixty-eight percent of the respondents rated their risks as lower or much lower than those of their peers, indicating a clear optimistic bias. The research also revealed that the students who exercised regularly rated their risk of coronary disease lower than those who did not do so. In addition, women perceived a number of risk markers to be more potent or causative factors than men did. A significant number of participants did not comprehend commonly understood causal relationships associated with heart disease risk. The findings in this preliminary investigation suggest that college men and women do not accurately perceive their risks for developing heart disease.     

NONLINEAR TUBE-FITTING FOR THE ANALYSIS OF ANATOMICAL AND FUNCTIONAL STRUCTURES

We are concerned with the estimation of the exterior surface and interior summaries of tube-shaped anatomical structures. This interest is motivated by two distinct scientific goals, one dealing with the distribution of HIV microbicide in the colon and the other with measuring degradation in white-matter tracts in the brain. Our problem is posed as the estimation of the support of a distribution in three dimensions from a sample from that distribution, possibly measured with error. We propose a novel tube-fitting algorithm to construct such estimators. Further, we conduct a simulation study to aid in the choice of a key parameter of the algorithm, and we test our algorithm with validation study tailored to the motivating data sets. Finally, we apply the tube-fitting algorithm to a colon image produced by single photon emission computed tomography (SPECT) and to a white-matter tract image produced using diffusion tensor imaging (DTI).