Ecological equivalence: a realistic assumption for niche theory as a testable alternative to neutral theory

Hubbell's 2001 neutral theory unifies biodiversity and biogeography by modelling steady-state distributions of species richness and abundances across spatio-temporal scales. Accurate predictions have issued from its core premise that all species have identical vital rates. Yet no ecologist believes that species are identical in reality. Here I explain this paradox in terms of the ecological equivalence that species must achieve at their coexistence equilibrium, defined by zero net fitness for all regardless of intrinsic differences between them. I show that the distinction of realised from intrinsic vital rates is crucial to evaluating community resilience. An analysis of competitive interactions reveals how zero-sum patterns of abundance emerge for species with contrasting life-history traits as for identical species. I develop a stochastic model to simulate community assembly from a random drift of invasions sustaining the dynamics of recruitment following deaths and extinctions. Species are allocated identical intrinsic vital rates for neutral dynamics, or random intrinsic vital rates and competitive abilities for niche dynamics either on a continuous scale or between dominant-fugitive extremes. Resulting communities have steady-state distributions of the same type for more or less extremely differentiated species as for identical species. All produce negatively skewed log-normal distributions of species abundance, zero-sum relationships of total abundance to area, and Arrhenius relationships of species to area. Intrinsically identical species nevertheless support fewer total individuals, because their densities impact as strongly on each other as on themselves. Truly neutral communities have measurably lower abundance/area and higher species/abundance ratios. Neutral scenarios can be parameterized as null hypotheses for testing competitive release, which is a sure signal of niche dynamics. Ignoring the true strength of interactions between and within species risks a substantial misrepresentation of community resilience to habitat los

Persistence Modeling for Assessing Marketing Strategy Performance

The question of long-run market response lies at the heart of any marketing strategy that tries to create a sustainable competitive advantage for the firm or brand. A key challenge, however, is that only short-run results of marketing actions are readily observable. Persistence modeling addresses the problem of long-run market-response quantification by combining into one measure of “net long-run impact†the chain reaction of consumer response, firm feedback and competitor response that emerges following the initial marketing action. In this paper, we (i) summarize recent marketing-strategic insights that have been accumulated through various persistence modeling applications, (ii) provide an introduction to some of the most frequently used persistence modeling techniques, and (iii) identify some other strategic research questions where persistence modeling may prove to be particularly valuable.long-run effectiveness;marketing strategy;time-series analysis

Persistence models and marketing strategy.

Marketing; Persistence; Models; Model; Strategy;

Learning unethical practices from a co-worker: the peer effect of Jose Canseco

This paper examines the issue of whether workers learn productive skills from their co-workers, even if those skills are unethical. Specifically, we estimate whether Jose Canseco, a star baseball player in the late 1980’s and 1990’s, affected the performance of his teammates by introducing them to steroids. Using panel data, we show that a player’s performance increases significantly after they played with Jose Canseco. After checking 30 comparable players from the same era, we find that no other baseball player produced a similar effect. Furthermore, the positive effect of Canseco disappears after 2003, the year that drug testing was implemented. These results suggest that workers not only learn productive skills from their co-workers, but sometimes those skills may derive from unethical practices. These findings may be relevant to many workplaces where competitive pressures create incentives to adopt unethical means to boost productivity and profits. Our analysis leads to several potential policy implications designed to reduce the spread of unethical behavior among workers.Peer Effects, Corruption, Crime, Externalities

Learning Unethical Practices from a Co-worker: The Peer Effect of Jose Canseco

This paper examines the issue of whether workers learn productive skills from their co-workers, even if those skills are unethical. Specifically, we estimate whether Jose Canseco, one of the best baseball players in the last few decades, affected the performance of his teammates. In his autobiography, Canseco claims that he improved the productivity of his teammates by introducing them to steroids. Using panel data on baseball players, we show that a player’s performance increases significantly after they played with Jose Canseco. After checking 30 comparable players from the same era, we find that no other baseball player produced a similar effect. Clearly, Jose Canseco had an unusual influence on the productivity of his peers. These results are consistent with Canseco’s controversial claims, and suggest that workers not only learn productive skills from their co-workers, but sometimes those skills may derive from unethical practices. These findings may be relevant to many workplaces where competitive pressures create incentives to adopt unethical means to boost productivity and profits.peer effects, corruption, crime, externalities

Chance and Competitive Advantage

Chance or randomness as a mechanism to induce performance heterogeneity among originally homogeneous firms has recently been introduced to the resource-based view of the firm. In this paper, we demonstrate how chance can engender variation in performance among initially identical firms even in the absence of firm-level capability differences. Departing from the positional school of strategy, we show how and when firms in systemic industries benefit from the chance of staking positions vis-à-vis competitors in complex technology landscapes. Expectedly, the chance of making choices early and repeatedly increases a firm’s profitability. Also, the value of repeated chance is higher during the early stages of an industry’s evolution than during its later phases. Importantly, however, this latter effect is exacerbated by increases in competition