Showing papers by "University of Michigan published in 1988"
TL;DR: In this article, structural equation models with latent variables are defined, critiqued, and illustrated, and an overall program for model evaluation is proposed based upon an interpretation of converging and diverging evidence.
Abstract: Criteria for evaluating structural equation models with latent variables are defined, critiqued, and illustrated. An overall program for model evaluation is proposed based upon an interpretation of converging and diverging evidence. Model assessment is considered to be a complex process mixing statistical criteria with philosophical, historical, and theoretical elements. Inevitably the process entails some attempt at a reconcilation between so-called objective and subjective norms.
19,160 citations
TL;DR: Experimental and quasi-experimental studies suggest that social isolation is a major risk factor for mortality from widely varying causes and the mechanisms through which social relationships affect health remain to be explored.
Abstract: Recent scientific work has established both a theoretical basis and strong empirical evidence for a causal impact of social relationships on health. Prospective studies, which control for baseline health status, consistently show increased risk of death among persons with a low quantity, and sometimes low quality, of social relationships. Experimental and quasi-experimental studies of humans and animals also suggest that social isolation is a major risk factor for mortality from widely varying causes. The mechanisms through which social relationships affect health and the factors that promote or inhibit the development and maintenance of social relationships remain to be explored.
7,669 citations
TL;DR: In this article, the authors present a methodology for optimal shape design based on homogenization, which is related to modern production techniques and consists of computing the optimal distribution in space of an anisotropic material that is constructed by introducing an infimum of periodically distributed small holes in a given homogeneous, i.i.
Abstract: Optimal shape design of structural elements based on boundary variations results in final designs that are topologically equivalent to the initial choice of design, and general, stable computational schemes for this approach often require some kind of remeshing of the finite element approximation of the analysis problem. This paper presents a methodology for optimal shape design where both these drawbacks can be avoided. The method is related to modern production techniques and consists of computing the optimal distribution in space of an anisotropic material that is constructed by introducing an infimum of periodically distributed small holes in a given homogeneous, i~otropic material, with the requirement that the resulting structure can carry the given loads as well as satisfy other design requirements. The computation of effective material properties for the anisotropic material is carried out using the method of homogenization. Computational results are presented and compared with results obtained by boundary variations.
5,858 citations
TL;DR: Assessing quality depends on whether one assesses only the performance of practitioners or also the contributions of patients and of the health care system, on how broadly health and responsibility for health are defined, and on whether the maximally effective or optimally effective care is sought.
Abstract: Before assessment can begin we must decide how quality is to be defined and that depends on whether one assesses only the performance of practitioners or also the contributions of patients and of the health care system; on how broadly health and responsibility for health are defined; on whether the maximally effective or optimally effective care is sought; and on whether individual or social preferences define the optimum. We also need detailed information about the causal linkages among the structural attributes of the settings in which care occurs, the processes of care, and the outcomes of care. Specifying the components or outcomes of care to be sampled, formulating the appropriate criteria and standards, and obtaining the necessary information are the steps that follow. Though we know much about assessing quality, much remains to be known. (JAMA1988;260:1743-1748)
5,353 citations
01 Jan 1988
TL;DR: This article posits a revised explanatory model which incorporates self-efficacy into the Health Belief Model, and predicts that the new formulation will more fully account for health-related behavior than did earlier formulations, and will suggest more effective behavioral interventions than have hitherto been available to health educators.
Abstract: The Health Belief Model, social learning theory (recently relabelled social cognitive theory), self-efficacy, and locus of control have all been applied with varying success to problems of explaining, predicting, and influencing behavior. Yet, there is conceptual confusion among researchers and practitioners about the interrelationships of these theories and variables. This article attempts to show how these explanatory factors may be related, and in so doing, posits a revised explanatory model which incorporates self-efficacy into the Health Belief Model. Specifically, self-efficacy is proposed as a separate independent variable along with the traditional health belief variables of perceived susceptibility, severity, benefits, and barriers. Incentive to behave (health motivation) is also a component of the model. Locus of control is not included explicitly because it is believed to be incorporated within other elements of the model. It is predicted that the new formulation will more fully account for health-related behavior than did earlier formulations, and will suggest more effective behavioral interventions than have hitherto been available to health educators.
4,772 citations
TL;DR: There is no a priori reason why machine learning must borrow from nature, but many machine learning systems now borrow heavily from current thinking in cognitive science, and rekindled interest in neural networks and connectionism is evidence of serious mechanistic and philosophical currents running through the field.
Abstract: There is no a priori reason why machine learning must borrow from nature. A field could exist, complete with well-defined algorithms, data structures, and theories of learning, without once referring to organisms, cognitive or genetic structures, and psychological or evolutionary theories. Yet at the end of the day, with the position papers written, the computers plugged in, and the programs debugged, a learning edifice devoid of natural metaphor would lack something. It would ignore the fact that all these creations have become possible only after three billion years of evolution on this planet. It would miss the point that the very ideas of adaptation and learning are concepts invented by the most recent representatives of the species Homo sapiens from the careful observation of themselves and life around them. It would miss the point that natural examples of learning and adaptation are treasure troves of robust procedures and structures. Fortunately, the field of machine learning does rely upon nature's bounty for both inspiration and mechanism. Many machine learning systems now borrow heavily from current thinking in cognitive science, and rekindled interest in neural networks and connectionism is evidence of serious mechanistic and philosophical currents running through the field. Another area where natural example has been tapped is in work on genetic algorithms (GAs) and genetics-based machine learning. Rooted in the early cybernetics movement (Holland, 1962), progress has been made in both theory (Holland, 1975; Holland, Holyoak, Nisbett, & Thagard, 1986) and application (Goldberg, 1989; Grefenstette, 1985, 1987) to the point where genetics-based systems are finding their way into everyday commercial use (Davis & Coombs, 1987; Fourman, 1985).
3,019 citations
TL;DR: In this paper, the authors provide a theoretical analysis of the process of competition for control of the target and empirical evidence that competition among bidding firms increases the returns to targets and decreases the return to acquirers, and that the supply of target shares is positively sloped.
1,880 citations
TL;DR: In this article, a review of the recent literature on social support and health and its relation to preexisting research and theory in the areas of social networks and social integration is presented, focusing on the need to better understand the structures and processes through which social relationships affect human health and well-being.
Abstract: This chapter reviews the recent literature on social support and health and its relation to preexisting research and theory in the areas of social networks and social integration. We identify crucial directions for future theoretical and empirical work, focusing on the need to better understand the structures and processes through which social relationships affect human health and well-being. Two elements of social relationship structure are distinguished: (a) social integration, which refers to the existence or quantity of social relationships, and (b) social network structure, referring to the structural properties that characterize a set of relationships. We further identify three social processes through which these structures may have their effects: (i) social support, which pertains to the emotionally or instrumentally sustaining quality of social relationships; (ii) relational demands and conflict, referring to the negative or conflictive aspects of social relationships; and (iii) social regulation...
1,723 citations
TL;DR: This paper argued that commitment, capacity, and expectations affect sensemaking during crisis and the severity of the crisis itself, and proposed that the core concepts of enactment may comprise an ideology that reduces the likelihood of crisis.
Abstract: SensertiEiking in crisis conditions is made more difficult because action that is instrumental to understanding the crisis often intensifies the crisis. This dilemma is interpreted from the perspective that people enact the environments which constrain them. It is argued that commitment, capacity, and expectations affect sensemaking during crisis and the severity of the crisis itself. It is proposed that the core concepts of enactment may comprise an ideology that reduces the hkelihood of crisis.
1,616 citations
TL;DR: It is concluded that the extent and severity of N limitation in the marine environment remain an open question, despite the fact that by the late seventies the evidence for P limitation had become so great that phosphorus control was recommended as the legislated basis for controlling eutrophication in North American and European inland waters.
Abstract: Phytoplankton can become limited by the availability of nutrients when light and temperature are adequate and loss rates are not excessive. The current paradigms for nutrient limitations in freshwater, estuarine, and marine environments are quite different. A review of the experimental and observational data used to infer P or N limitation of phytoplankton growth indicates that P limitation in freshwater environments can be demonstrated rigorously at several hierarchical levels of system complexity, from algal cultures to whole lakes. A similarly rigorous demonstration of N limitation has not been achieved for marine waters. Therefore, we conclude that the extent and severity of N limitation in the marine environment remain an open question. Culture studies have established that internal cellular concentrations of nutrients determine phytoplankton growth rates, and these studies have shown that it is often difficult to relate growth rates to external concentrations, especially in natural situations. This should lead to a greater reliance on the composition of particulate matter and biomass-based physiological rates to infer nutrient limitation. Such measurements have demonstrated their utility in a wide variety of freshwater and marine environments, and, most importantly, they can be applied to systems that are difficult to manipulate experimentally or budget accurately. Dissolved nutrient concentrations are most useful in determining nutrient loading rates of aquatic ecosystems. The relative proportions of nutrients supplied to phytoplankton can be a strong selective force shaping phytoplankton communities and affecting the biomass yield per unit of limiting nutrient. A current dogma of aquatic science is that marine and estuarine phytoplankton tend to be nitrogen limited, while freshwater phytoplankton tend to be phosphorus limited. Carpenter and Capone (1983) documented the preeminence of N studies in the literature on brackish and marine ecosystems. In 1970 there were equal numbers of references per year to N and P. The decade of the seventies saw a nearly fourfold increase in references to N, while the number of P references per year remained essentially unchanged. No trend was evident for the freshwater literature despite the fact that by the late seventies the evidence for P limitation had become so great that phosphorus control was recommended as the legislated basis for controlling eutrophication in North American and European inland waters (e.g.
1,594 citations
TL;DR: Palmer et al. as mentioned in this paper showed that macrophages immunostimulated with interferon gamma and Escherichia coli lipopolysaccharide synthesize NO2-, NO3-, and citrulline from L-arginine by oxidation of one of the two chemically equivalent guanido nitrogens.
Abstract: Previous studies have shown that murine macrophages immunostimulated with interferon gamma and Escherichia coli lipopolysaccharide synthesize NO2-, NO3-, and citrulline from L-arginine by oxidation of one of the two chemically equivalent guanido nitrogens. The enzymatic activity for this very unusual reaction was found in the 100,000g supernatant isolated from activated RAW 264.7 cells and was totally absent in unstimulated cells. This activity requires NADPH and L-arginine and is enhanced by Mg2+. When the subcellular fraction containing the enzyme activity was incubated with L-arginine, NADPH, and Mg2+, the formation of nitric oxide was observed. Nitric oxide formation was dependent on the presence of L-arginine and NADPH and was inhibited by the NO2-/NO3- synthesis inhibitor NG-monomethyl-L-arginine. Furthermore, when incubated with L-[guanido-15N2]arginine, the nitric oxide was 15N-labeled. The results show that nitric oxide is an intermediate in the L-arginine to NO2-, NO3-, and citrulline pathway. L-Arginine is required for the activation of macrophages to the bactericidal/tumoricidal state and suggests that nitric oxide is serving as an intracellular signal for this activation process in a manner similar to that very recently observed in endothelial cells, where nitric oxide leads to vascular smooth muscle relaxation [Palmer, R. M. J., Ashton, D. S., & Moncada, S. (1988) Nature (London) 333, 664-666].
01 Apr 1988
TL;DR: An algorithm for computing the Euclidean distance between a pair of convex sets in R/sup m/ has special features which makes its application in a variety of robotics problems attractive.
Abstract: An algorithm for computing the Euclidean distance between a pair of convex sets in R/sup m/ is described. Extensive numerical experience with a broad family of polytopes in R/sup 3/ shows that the computational cost is approximately linear in the total number of vertices specifying the two polytopes. The algorithm has special features which makes its application in a variety of robotics problems attractive. These features are discussed and an example of collision detection is given. >
TL;DR: The present conceptual framework provides insights into principles of motor performance, and it links the study of physical action to research on sensation, perception, and cognition, where psychologists have been concerned for some time about the degree to which mental processes incorporate rational and normative rules.
Abstract: A stochastic optimized-submovement model is proposed for Pitts' law, the classic logarithmic tradeoff between the duration and spatial precision of rapid aimed movements. According to the model, an aimed movement toward a specified target region involves a primary submovement and an optional secondary corrective submovement. The submovements are assumed to be programmed such that they minimize average total movement time while maintaining a high frequency of target hits. The programming process achieves this minimization by optimally adjusting the average magnitudes and durations of noisy neuromotor force pulses used to generate the submovements. Numerous results from the literature on human motor performance may be explained in these terms. Two new experiments on rapid wrist rotations yield additional support for the stochastic optimizedsubmovement model. Experiment 1 revealed that the mean durations of primary submovements and of secondary submovements, not just average total movement times, conform to a square-root approximation of Pitts' law derived from the model. Also, the spatial endpoints of primary submovements have standard deviations that increase linearly with average primary-submovement velocity, and the average primary-submovement velocity influences the relative frequencies of secondary submovements, as predicted by the model. During Experiment 2, these results were replicated and extended under conditions in which subjects made movements without concurrent visual feedback. This replication suggests that submovement optimization may be a pervasive property of movement production. The present conceptual framework provides insights into principles of motor performance, and it links the study of physical action to research on sensation, perception, and cognition, where psychologists have been concerned for some time about the degree to which mental processes incorporate rational and normative rules. An enduring issue in the study of the human mind concerns of mathematical probability theory and statistical decision thethe rationality and optimality of the mental processes that guide ory (e.g., see Edwards, 1961; Edwards, Lindman, & Savage,
TL;DR: In this paper, the authors explore the characteristics of emerging organizations and suggest that emerging organizations can be identified by four properties: intentionality, resources, boundary, and exchange, and make suggestions for selecting samples for research on emerging organizations.
Abstract: This article explores the characteristics of emerging organizations and suggests that emerging organizations can be identified by four properties: intentionality, resources, boundary, and exchange. These properties are defined and discussed. Suggestions are made for selecting samples for research on emerging organizations. Implications for research and theory on new and emerging organizations are discussed.
TL;DR: There is a wide body of evidence to suggest the existence of at least three distinct opioid receptor types in the CNS, referred to as μ, δ, and κ, and their relation to the opioid peptides is discussed.
TL;DR: A piecewise-smooth surface model for image data that possesses surface coherence properties is used to develop an algorithm that simultaneously segments a large class of images into regions of arbitrary shape and approximates image data with bivariate functions so that it is possible to compute a complete, noiseless image reconstruction based on the extracted functions and regions.
Abstract: The solution of the segmentation problem requires a mechanism for partitioning the image array into low-level entities based on a model of the underlying image structure. A piecewise-smooth surface model for image data that possesses surface coherence properties is used to develop an algorithm that simultaneously segments a large class of images into regions of arbitrary shape and approximates image data with bivariate functions so that it is possible to compute a complete, noiseless image reconstruction based on the extracted functions and regions. Surface curvature sign labeling provides an initial coarse image segmentation, which is refined by an iterative region-growing method based on variable-order surface fitting. Experimental results show the algorithm's performance on six range images and three intensity images. >
TL;DR: The phonological-core variable-difference model provides a way to conceptualize the differences between dyslexic and garden-variety poor readers and highlights the importance of viewing the concept of dyslexia as the outcome of the application of an arbitrary criterion in a continuous distribution.
Abstract: A coherent conception of dyslexia has been difficult to arrive at because research findings have continually created logical paradoxes for the psychometric definition of reading disability. This paper develops the phonological-core variable-difference model. This model of the cognitive characteristics of dyslexic children is one of the few that does not create psychometric paradoxes of the type that have plagued the learning disabilities field. The model provides a way to conceptualize the differences between dyslexic and garden-variety poor readers. The model highlights the importance of viewing the concept of dyslexia as the outcome of the application of an arbitrary criterion in a continuous distribution, thus avoiding the connotations of discreteness that have continually undermined our understanding of reading disability.
TL;DR: The importance of the critical fossils seems to reside in their relative primitive‐ness, and the simplest explanation for their more conservative nature is that they have had less time to evolve.
TL;DR: In this article, two studies investigating the growth patterns of new ventures are presented, and a stage-of-growth model is proposed to apply specifically to technology-based new ventures.
Abstract: Two studies investigating the growth patterns of new ventures are presented. In the first study, a stage-of-growth model theorized to apply specifically to technology-based new ventures was develop...
TL;DR: Experiments are reported investigating whether abrupt onset is simply one member of a large class of stimulus characteristics, all of which are capable of capturing attention, and whether these also could elicit shifts of attention.
Abstract: Yantis and Jonides (1984) demonstrated that the detection of a target in visual search was markedly enhanced when the target was presented as an abruptly onset character embedded among other characters whose presentation was not characterized by abrupt onset. This effect was attributed to a shift of attention caused by abrupt onset. In the present article, we report experiments investigating whether abrupt onset is simply one member of a large class of stimulus characteristics, all of which are capable of capturing attention. To test this possibility, we compared abrupt onset with differences in stimulus luminance and hue to determine whether these also could elicit shifts of attention. They could not.
TL;DR: This paper examined the effects of country-of-origin and brand name cues on consumer evaluations of uni-national and bi-national products and estimated the perceived values of such cues.
Abstract: This study examines the effects of country-of-origin and brand name cues on consumer evaluations of uni-national and bi-national products and estimates the perceived values of such cues. From personal interviews with a regional quota sample of household residents, the study found the salience of country-of-origin in product evaluations under within-subject experimental design. Finally, managerial implications are discussed in regards to international branding and sourcing strategies.
TL;DR: It is demonstrated that risk of predation by largemouth bass was 40-80 times as great for small bluegills in the open water as for those in the vegetation, and that the pelagic zone is the more profitable habitat for all size classes of the bluegill.
Abstract: The bluegill sunfish (Lepomis macrochirus) undergoes several habitat shifts between the littoral and pelagic zones of small lakes during its life history. After hatching in the littoral zone, bluegill fry migrate to the pelagic zone to feed on zooplankton. In this study the fry then returned to the littoral zone in four different lakes at a relatively constant size of 12.5 mm standard length. Several years are spent feeding in the littoral zone vegetation before the bluegill again shifts to feeding on zooplankton, first in the water column above littoral vegetation and subsequently in the true pelagic zone. This shift to feeding on zooplankton occurred at a specific body size within a lake, but the size ranged from 50 to 83 mm among five different lakes. The size at which the shift occurred was directly correlated with the density of the major predator of the bluegill in these lakes, the largemouth bass (Micropterus salmoides). We demonstrate that the bluegill is faced with a growth (or feeding) rate-predation risk trade-off in making these habitat shifts. Analyses of stomach contents, the growth of small fish caged in the pelagic zone, and predictions of foraging rates in both habitats all indicate that the pelagic zone is the more profitable habitat for all size classes of the bluegill. Through a series of pond experiments we further show that risk of predation by largemouth bass was 40-80 times as great for small bluegills in the open water as for those in the vegetation. We interpret the patterns of habitat use by the bluegill in terms of a model that explicitly weights the costs (predation) and benefits (growth) of making a size-specific habitat shift to the pelagic. Finally, we discuss evidence that the bluegill can facultatively respond to changes in feeding rates and predation risk, and the consequences of such ontogenetic habitat shifts to community dynamics.
TL;DR: In this paper, the authors consider a class of feedback systems arising from the regulation of time-varying discrete-time systems using optimal infinite-horizon and movinghorizon feedback laws, characterized by joint constraints on the state and the control, a general nonlinear cost function and nonlinear equations of motion possessing two special properties.
Abstract: Stability results are given for a class of feedback systems arising from the regulation of time-varying discrete-time systems using optimal infinite-horizon and moving-horizon feedback laws. The class is characterized by joint constraints on the state and the control, a general nonlinear cost function and nonlinear equations of motion possessing two special properties. It is shown that weak conditions on the cost function and the constraints are sufficient to guarantee uniform asymptotic stability of both the optimal infinite-horizon and moving-horizon feedback systems. The infinite-horizon cost associated with the moving-horizon feedback law approaches the optimal infinite-horizon cost as the moving horizon is extended.
TL;DR: In this paper, the Correlates of War project has been used to define and measure material capabilities in international politics models, and the ambiguity of the notion is defined and measured in operational terms.
Abstract: Given the central role of the concept of material capabilities in international politics models, and the ambiguity of the notion, it is essential that we define and measure it in operational terms. Such efforts have a long history and, given the multiplicity of interpretations as well as the difficulty of validation, we can expect alternative indicators to be put forth with some regularity well into the future. Herein, some of the assumptions, procedures, and implications of the Correlates of War project effort. First, we treat “power” as the generic concept, defined as the capacity of a state (or other actor) both to exercise influence and to resist influence attempts. That capacity is a function of, inter alia, geography, political organization and legitimacy, definition of “interests,” elite competence, and, of course, material capabilities. We see the last of these as falling along three dimensions: demographic, industrial, and military. The paper spells out the measurement problems, theoretic premise...
TL;DR: Empirical andoretical work has led to a deeper understanding of the role of other factors in the evolution of cooperation: the number of players, the range of possible choices, variation in the payoff structure, noise, the shadow of the future, population dynamics, and population structure.
Abstract: Axelrod's model of the evolution of cooperation was based on the iterated Prisoner's Dilemma. Empirical work following this approach has helped establish the prevalence of cooperation based on reciprocity. Theoretical work has led to a deeper understanding of the role of other factors in the evolution of cooperation: the number of players, the range of possible choices, variation in the payoff structure, noise, the shadow of the future, population dynamics, and population structure. C OOPERATION IS A TOPIC OF CONTINUING INTEREST FOR the social and biological sciences. A theory of cooperation based upon reciprocity (1-3) has engendered a wide literature concerning the evolution of cooperation. In this article, we survey this literature in order to determine what new insights have been gained. Although we shall concentrate on theoretical work, it is important to note that scholars have been active in pursuing empirical applications of the theory. Huth (4) found that military conflict during the last century was most successfully deterred when a challenge was met with reciprocity. Cooperation based on reciprocity has been supported for vampire bats (5, 6), vervet monkeys (7), and sessile invertebrates (8). Experimental simulations of defection have been presented to stickleback fish (9) and tree swallows (10); the findings are consistent with reciprocity. On the other hand, Nol (11) rejected reciprocity as an explanation of cooperation between the sexes in chick-rearing by the American oyster catcher, arguing that data on foraging trips and energy use support a theory based on the efficient allocation of energy by the birds. Other investigators have pointed to the difficulties in determining whether observed cooperation is due to a tit-for-tat-like process (12). Despite these difficulties, cooperation based upon reciprocity has received substantial empirical support.
TL;DR: Recently discovered theories of heterogeneous reaction kinetics have dramatic consequences, such as fractal orders for elementary reactions, self-ordering and self-unmixing of reactants, and rate coefficients with temporal "memories".
Abstract: Classical reaction kinetics has been found to be unsatisfactory when the reactants are spatially constrained on the microscopic level by either walls, phase boundaries, or force fields. Recently discovered theories of heterogeneous reaction kinetics have dramatic consequences, such as fractal orders for elementary reactions, self-ordering and self-unmixing of reactants, and rate coefficients with temporal "memories." The new theories were needed to explain the results of experiments and supercomputer simulations of reactions that were confined to low dimensions or fractal dimensions or both. Among the practical examples of "fractal-like kinetics" are chemical reactions in pores of membranes, excitation trapping in molecular aggregates, exciton fusion in composite materials, and charge recombination in colloids and clouds.
TL;DR: The hypotheses that, compared with soleus and EDL muscles of young and adult mice, those from aged mice develop decreased maximum tetanic force (P0, mN) and specific P0 (N/cm2) and that no significant differences occur for contraction time, half‐relaxation time, or force‐velocity relationship are tested.
Abstract: 1 Comparisons were made in vitro at 25 degrees C among soleus and extensor digitorum longus (EDL) muscles from young (2-3 months), adult (9-10 months), and aged (26-27 months) male mice We tested the hypotheses that, compared with soleus and EDL muscles of young and adult mice, those from aged mice develop decreased maximum tetanic force (P0, mN) and specific P0 (N/cm2), and that no significant differences occur for contraction time, half-relaxation time, or force-velocity relationship 2 For the aged mice, the P0 of the soleus muscles and EDL muscles were 78 and 73% respectively of the values for adult mice The specific P0 of EDL muscles of aged mice was 78% of the value of 23 N/cm2 obtained for young and adult mice For soleus muscles, the specific P0 of 21 N/cm2 did not change with age 3 Compared to values for young and adult mice, the contraction and half-relaxation times of soleus muscles from aged mice were increased, but the overall force-velocity relationships of soleus and EDL muscles did not change The pooled values for the maximum velocity of unloaded shortening extrapolated from the force-velocity relationship of soleus and EDL muscles were 46 and 101 fibre lengths/s, respectively 4 The decrease in the specific P0 of the EDL muscle with ageing must result from either a decrease in the number of cross-bridges in the driving stroke or a decrease in the force developed by each cross-bridge
TL;DR: Four empirical studies were conducted to identify tactics of intrasexual mate competition and to test four evolution-based hypotheses, which supported the basic hypotheses but revealed several predictive failures and unanticipated findings.
Abstract: Darwin's theory of sexual selection suggests that individuals compete with members of their own sex for reproductively relevant resources held by members of the opposite sex. Four empirical studies were conducted to identify tactics of intrasexual mate competition and to test four evolution-based hypotheses. A preliminary study yielded a taxonomy of tactics. Study 1 used close-friend observers to report performance frequencies of 23 tactics to test the hypotheses. Study 2 replicated Study 1's results by using a different data source and subject population. Study 3 provided an independent test of the hypotheses in assessing the perceived effectiveness of each tactic for male and female actors. Although the basic hypotheses were supported across all three studies, there were several predictive failures and unanticipated findings. Discussion centers on the heuristic as well as predictive role of evolutionary theory, and on implications for other arenas of intrasexual competition.
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TL;DR: This paper used the identifying assumption that only supply shocks, such as shocks to technology, oil prices, and labor supply affect output in the long run, but only in the short run.
Abstract: What shocks account for the business cycle frequency and long run movements of output and prices? This paper addresses this question using the identifying assumption that only supply shocks, such as shocks to technology, oil prices, and labor supply affect output in the long run Real and monetary aggregate demand shocks can affect output, but only in the short run This assumption sufficiently restricts the reduced form of key macroeconomic variables to allow estimation of the shocks and their effect on output and price at all frequencies Aggregate demand shocks account for about twenty to thirty percent of output fluctuations at business cycle frequencies Technological shocks account for about one-quarter of cyclical fluctuations, and about one-third of output's variance at low frequencies Shocks to oil prices are important in explaining episodes in the 1970's and 1980's Shocks that permanently affect labor input account for the balance of fluctuations in output, namely, about half of its variance at all frequencies