design and analysis of simulated consumer choice or allocation experiments an approach based on aggregate data the authors integrate concepts in conjoint analysis and discrete choice theory in econometrics to develop a new approach to the design and analysis of controlled consumer choice or resource allocat

utility covariances and context effects in conjoint mnp models experimental conjoint choice analysis is among the most frequently used methods for measuring and analyzing consumer preferences the data from such experiments have been typically analyzed with the multinomial logit mnl model however there are several problems associated with the standard mnl model because it is based on the assumption that the error terms of the underlying random utilities are independent across alternatives choice sets and subjects the multinomial probit model mnp is well known to alleviate this assumption of independence of the error terms accounting for covariances in utilities in modeling choice experiments with the mnp is important because variation of the coefficients in the choice model may occur due to context effects previous research has shown that subjects utilities for alternatives depend on the choice context that is the particular set of alternatives evaluated simonson and tversky s tradeoff contrast principle describes the effect of the choice context on attribute importance and patterns of choice they distinguish local contrast effects which are caused by the alternatives in the offered set only and background contrast effects which are due to the influence of alternatives previously considered in choice experiments these effects are hypothesized to cause correlations in the utilities of alternatives within and across choice sets respectively the purpose of this study is to develop an mnp model for conjoint choice experiments this model is important for a more detailed study of choice patterns in those experiments in developing the mnp model for conjoint choice experiments several hurdles need to be taken related to the identification of the model and to the prediction of holdout profiles to overcome those problems we propose a random coefficients rc model that assumes a multivariate normal distribution of the regression coefficients with a rank one factor structure on the covariance matrix of these regression coefficients the parameters in this covariance matrix can be used to identify which attributes and levels of attributes are potentional sources of dependencies between the alternatives and choice sets in a conjoint choice experiment we present several versions of this model moreover for each of these models we allow utilities to be either correlated or independent across choice sets the independent probit ip model is used as a benchmark given the dimensionality of the integrations involved in computing the choice probabilities the models are estimated with simulated likelihood where simulations are used to approximate the integrals involved in the choice probabilities we apply and compare the models in two conjoint choice experiments in both applications the random coefficients mnp model that allows choices in different choice sets to be correlated rc displays superior fit and predictive validity compared with all other models we hypothesize that the difference in fit occurs because the rc model accommodates correlations among choice sets that are caused by background contrast effects whereas the model that treats choice sets as independent irc accounts for local contrast effects only the irc model shows superior model fit compared with the ip model but its predictions are worse than those of the ip model we find differences in the importance of local and background contrast effects for choice sets containing different numbers of alternatives the background contrast effect may be stronger for smaller choice sets whereas the local contrast effect may be stronger for bigger choice sets we illustrate the differences in simulated market shares that are obtained from the rc irc and ip models in three hypothetical situations product modification product line extension and the introduction of a me too brand in all of those situations substantially different market shares are predicted by the three models which illustrates the extent to which erroneous predictions may be obtained from the misspecified irc and ip models

an analysis of the tradeoff between advertising and price discounting the authors examine an important influence on the price advertising tradeoff the ratio of price and advertising elasticities their theoretical analysis stresses the centrality of the elasticity r

optimum distribution free tests and further evidence of heteroscedasticity in the market model in this paper several powerful distribution free tests for heteroscedasticity are introduced and are used to test the hypothesis of constant variance in the market model these tests are noted for their flexibility in specifying alternative hypotheses it is found that the assumption of homoscedasticity is untenable for the majority of stocks analyzed the implications of this finding for the efficient estimation of the parameters of the market model are also discussed

minimum market share this paper analyzes a specific model of oligopolistic competition involving product differentiation marketing activities and economies of scale in production this model is consistent with sales response models which have been justified on theoretical and empirical bases it is shown that at a nash equilibrium each firm must have market share equal to zero or greater than a threshold value this result has implications for determination of minimum firm size the effectiveness of a low market share strategy entry barriers and the likelihood of concentration in an industry the paper explores these implications and relates them to various theories and hypotheses in industrial organization and strategic planning

understanding long run african growth colonial institutions or colonial education abstract long term growth in developing countries has been explained in four frameworks extractive colonial institutions acemoglu et al 2001 colonial legal origin la porta et al 2004 geography gallup et al 1998 and colonial human capital glaeser et al 2004 in this paper we test the colonial human capital explanation for sub saharan africa controlling for legal origin and geography utilising data on colonial era education we find that instrumented human capital explains long term growth better and shows greater stability over time than instrumented measures for extractive institutions we suggest that the impact of the disease environment on african long term growth runs through a human capital channel rather than an extractive institutions channel the effect of education is robust to including variables capturing legal origin and geography which have additional explanatory power

competitive pricing by a price leader we examine the problem of pricing in a market where one brand acts as a price leader we develop a procedure to estimate a leader s price rule which is optimal given a sales target objective and allows for the inclusion of demand forecasts we illustrate our estimation procedure by calibrating this optimal price rule for both the leader and the follower using data on past sales and prices from the mid size sedan segment of the u s automobile market our results suggest that a leader follower system stackelberg seems more consistent with the pricing behavior in this market than a mutually independent pricing rule nash we also find that our optimal price rule explains this market data better than other pricing schemes that do not account for optimizing behavior on the part of the leader and the follower

what determines productivity in senegal sectoral disparities and the dual labour market abstract this paper analyses the output gap between the formal and informal sectors in senegal using a matched employer employee database while the production process in some informal sub sectors is similar to the one in the formal sector there is evidence that the economy is deeply cleaved between productive and non productive firms within the informal sector and between voluntary and involuntary jobs on a labour market which proves to be dual we find that education externalities are significant although modest in both sectors and that the differences in human and physical capital account for about two thirds of the output gap

modeling inertia and variety seeking tendencies in brand choice behavior theories of exploratory behavior suggest that inertia and variety seeking tendencies may coexist within the individual implying that the same individual may exhibit inertia and variety seeking at different times depending on his her choice history past research has not allowed for such within consumer variability in these tendencies the purpose of this study is to present a choice model that allows us to identify such hybrid behavior i e a mixture of inertia and variety seeking and to distinguish hybrid behavior from simpler types of behavior such as pure inertia pure variety seeking and zero order behavior the model is estimated at the household level using panel data for three product classes covering a total of 1069 households the empirical analysis shows that more than half the households analyzed exhibited hybrid behavior rather than simpler types of behavior

environment market share and market power in this paper we develop a process model relating market share to firm profits in particular we specify average price and average cost equations as a function of previous year market share position changes in market share environmental conditions and interactions of environmental conditions with the lagged market position and market share change variables we estimate these equations using pims data after controlling for unobservable factors our results suggest that firms with high market shares derive no extra market power benefits except if they operate in environments with little buyer power instead environmental factors and changes in market share most strongly influence price and cost an analysis of the market share associated with maximal firm profits indicates that for the majority of firms in our sample steadily increasing market share does not always associate with increasing profits giving credence to the proposition that more market share is not always better

chapter 4 competitive marketing strategies game theoretic models publisher summary this chapter reviews the key developments in the understanding of competitive marketing strategies product price advertising and distribution competition are all addressed while the emphasis is on models the chapter surveys the empirical literature as well there is a significant amount of empirical work to report but the ratio of theoretical to empirical work is nevertheless unpleasantly large much progress has been made in the last ten years or so in the study of competitive marketing strategies most of this chapter has been theoretical using simple models of firm and consumer behavior these models serve the function of demonstrating rigorously the existence of certain effects factors which need to be considered in analyzing real world competition

a friction model for describing and forecasting price changes this paper presents a new friction model for describing the price changes of a product or brand over time and for forecasting both the timing and magnitude of such changes from one period to the next after a review of the related pricing literature we present our model and a modified controlled random search procedure for estimating its parameters the model is applied to describe and forecast the weekly mortgage interest rates for a local bank in the philadelphia area finally limitations and several potential applications of this methodology are discussed

investigating the effects of store brand introduction on retailer demand and pricing behavior researchers have recently been interested in studying the drivers of store brand success as well as factors that motivate retailers to introduce store brands in this paper we study the effects of the introduction of a store brand into a particular product category specifically we are interested in the effect of store brand introduction on the demand as well as on the supply side on the demand side we investigate the changes in preferences for the national brands and price elasticities in the category on the supply side we study the effects of the new entrant on the interactions between the national brand manufacturers and the retailer introducing the store brand including how these interactions influence the retailer s pricing behavior in doing so we are also able to test whether the observed data are consistent with some of the commonly used assumptions regarding retailer pricing behavior for the demand specification we use a random coefficients logit model that allows for consumer heterogeneity the model parameters are estimated using aggregate data while explicitly accounting for endogeneity in retail prices our empirical results obtained from the oats product category based on store level data from a multistore retail chain indicate that the store brand introduction generates notable changes within the category the store brand introduction coincides with an increase in the retailer s margins for the national brand we find that the preferences for the national brand are relatively unaffected by the introduction of the store brand while consumers are in general more price sensitive in terms of elasticities than they were prior to store brand introduction a statistical test of the differences inmean price elasticities across stores and between the two regimes fails to reject the hypothesis of no change in these elasticities elasticities in specific stores however do increase after the store brand is introduced we also find that there is considerable heterogeneity in the preferences for the store brand on the supply side we test several forms of manufacturer retailer interactions to identify retailer pricing behavior most consistent with the data our results indicate that the data reject several commonly imposed forms of interactions in examining the nature of manufacturer interactions with the retailer we find that the manufacturer of the national brand appears to take a softer stance in its interactions with the retailer subsequent to store brand entry this finding is consistent with academic research and with articles in the popular press which suggest that the store brand enhances the retailer s bargaining ability vis a vis the manufacturers of the national brands we also provide results from a second product category frozen pasta that are largely consistent with those found in the oats category

competitive maps the structure underlying asymmetric cross elasticities a special case of three mode factor analysis is used to portray the systematic structure underlying asymmetric cross elasticities for a broad class of market share attraction models analysis of the variation over retail outlets and weeks reveals competitive patterns corresponding to sales for the major brands in the market as well as patterns reflecting shelf price competition analysis of the brand domain results in a joint space one set of brand positions portrays how brands exert influence over the competition the other set of points portrays how brands are influenced by others the interset distances angles provide direct measures of competitive pressures maps are formed as spatial representations of each of the competitive patterns discovered

an ideal point probabilistic choice model for heterogeneous preferences this paper presents a new ideal point probabilistic choice model unlike the model suggested by cooper and nakanishi cooper l g m nakanishi 1983 two logit models for external analysis of preferences psychometrika48 4 607 619 which attempts to capture choices via a single ideal point the proposed model though based on aggregate data allows for heterogeneity in preferences by estimating a distribution of ideal points the model accounts for substitutability among choice alternatives and alleviates one of the major sources for the violation of the independence from irrelevant alternatives property it is demonstrated that the final form of the model is a multinomial probit with a covariance matrix that depends on the relative position of the choice alternatives an empirical application is provided and the resulting parameters are compared to the distributions of ideal points and attribute weights obtained via linmap at the individual level and via both the logit and probit versions of the model proposed by cooper and nakanishi at the aggregate level

an experimental and theoretical analysis of price matching refund policies abstract price matching refund policies or offers by firms to match competitor s prices are common in both consumer and industrial marketing much of the previous theoretical work in economics suggests that price matching refunds are associated with higher prices in contrast the trade press postulates that price matching policies are associated with lower prices given these inconsistent views regarding price matching policies the authors experimentally examine how consumers view and interpret such policies and then develop a model that incorporates these consumer interpretations as well as asymmetries across stores in the model the asymmetry across stores is the key to deriving the conditions under which a signaling equilibrium exists in the presence of price matching policies the critical point is that the competition reducing and price discrimination effects which seem to form the basis of most of the previous theoretical literature can be counteracted by the presence of differentiated firms

a heterogeneous conditional logit model of choice aggregate forecasts using mcfadden s conditional logit model of discrete choice harbor the unrealistic implicit assumption of a random utility distribution that is homogeneous across both alternatives and individuals this article relaxes that assumption a choice model is developed that describes the random utility component as a probability mixture model some numerical results illustrate that the derived model is not constrained by the independence of irrelevant alternatives property an experimental test of visual perceptions demonstrates the potential superiority of the model

a probabilistic choice model for market segmentation and elasticity structure marketing scholars commonly characterize market structure by studying the patterns of substitution implied by brand switching though the approach is useful it typically ignores the destabilizing

order of entry as a moderator of the effect of the marketing mix on market share order of entry has been demonstrated to have a significant effect on market share a number of explanations for this effect have been suggested in the marketing and strategy literatures to date the market share advantage gained by pioneers has typically been treated as a main effect an automatic regularity treating order of entry as a main effect implies that there is no penalty on the effectiveness of a brand s marketing instruments for late entry and that a late entrant can compensate for being late by dedicating sufficient marketing resources to their product in this study we investigate the influence of order of entry into a market on the effectiveness of a firm s marketing mix decisions by asking the question can followers compensate for not being first by their marketing mix decisions also even if they can compensate for being late does this effort become increasingly more difficult with later entry that is are there asymmetries in the effectiveness of a brand s marketing mix variables that relate to its order of entry into the market or as has been typically assumed to date is order of entry strictly a main effect an asymmetry exists for example if the market response to advertising is different for the first entrant versus the second or third entrant an asymmetry also exists if the effects of say a price change by the first entrant on the second entrant are different than the effects on the third entrant we develop a market share attraction model where the parameters vary as a function of order of entry our main contribution is in modeling the sources of order of entry advantage as asymmetries in the effectiveness of a brand s marketing instruments hence distinct from previous research we explain why there are inherent order of entry effects this paper is potentially of interest to researchers developing market share models and studying the effectiveness of marketing mix variables the substantive implication of our results concern directly academics interested in marketing strategy as well as the practicing marketing strategists we model asymmetries in the market response of early entrants versus late entrants using data from two durables and three nondurables categories with one exception all data sets are established from the inception of the category and hence do not suffer from the possible bias of excluding pioneers who have failed results show that asymmetries in the effectiveness of a brand s marketing mix variables are an essential source of order of entry effects we find that the main effects of order of entry are minimal order of entry effects do not necessarily lead to lower shares but overcoming these effects is not without substantial cost to the late entrant our results support previous research that has demonstrated advantages to early entry in addition we provide guidelines for how late entrants should compete later entry tends to reduce a competitor s price sensitivity suggesting that they not instigate in a price war with earlier entrants in order to gain share order of entry tends to decrease response to quality and to promotion to achieve the same impact on market share later entrants need a bigger change in quality and need to spend more on promotion our data did not support an asymmetric effect on advertising

testing predicted choices against observations in probabilistic discrete choice models probabilistic discrete choice models such as multinomial logit models are widely used to predict changes in market shares or total demand resulting from changes in policy variables under management control these models often are evaluated in terms of their ability to predict choices in a holdout sample this paper presents a new test for comparing predicted and observed choices the results of a monte carlo experiment indicate that the new test has good finite sample properties and high power in several circumstances likely to arise frequently in applications

the informal sector in developed and less developed countries a literature survey the main goal of this study is two fold 1 to provide ageneral overview of the contributions to the literature on theinformal sector with a special focus on the public choiceapproach and 2 to compare these contributions across twoinstitutionally different types of countries developed andless developed developing and transition countries thepaper focuses on the criteria used to define the informalsector the relationship between the formal and informaleconomy tax evasion and public choice analysis it isstressed throughout this paper that the distinction betweenthe two types of countries is of key importance

a nested logit model of space and water heat system choice this paper estimates a nested logit model for space heat and water heat choice using data from the 1980 pacific northwest energy survey pnw the estimated structure involves six alternative space heat systems and three alternative water heat fuel types operating and capital costs are predicted for each residence using an energy thermal model to relax the independence of irrelevant alternatives assumption we employ a family of nested logit models we illustrate the two step estimation method and use a lagrange multiplier test for nested logit structure finally we use the estimated models to forecast the market shares of alternative space heat systems under an assumed scenario for the course of relative fuel prices

the choice theory approach to market research this paper surveys economic choice theory stressing developments that permit use of data from psychometric and conjoint experiments to produce market demand forecasts alternatives to the widely used multinomial logit model are summarized and a new method for estimating multinomial probits is described an integration of choice models with attitudinal scaling and perceptual mapping within a latent variable system is described estimation of such systems under either random effects or fixed effects descriptions of heterogeneity across individuals is discussed issues in the use of choice models to describe responses from conjoint experiments are presented new regression diagnostic tests for the consistency of multinomial logit representations are discussed

asymmetric and neighborhood cross price effects some empirical generalizations this paper provides some empirical generalizations regarding how the relative prices of competing brands affect the cross price effects among them particular focus is on the asymmetric price effect and the neighborhood price effect the asymmetric price effect states that a price promotion by a higher priced brand affects the market share of a lower priced brand more so than the reverse the neighborhood price effect states that brands that are closer to each other in price have larger cross price effects than brands that are priced farther apart the main objective of this paper is to test if these two effects are generalizable across product categories and to assess which of these two effects is stronger while the neighborhood price effect has not been rigorously tested in past research the asymmetric price effect has been validated by several researchers however these tests of asymmetric price effect have predominantly used elasticity as the measure of cross price effect the cross price elasticity measures the percentage change in market share or sales of a brand for 1 change in price of a competing brand we show that asymmetries in cross price elasticities tend to favor the higher priced brand simply because of scaling effects due to considering percentage changes furthermore several researchers have used logit models to infer asymmetric patterns we also show that inferring asymmetries from conventional logit models is incorrect to account for potential scaling effects we consider the absolute cross price effect defined as the change in market share percentage points of a target brand when a competing brand s price changes by one percent of the product category price the advantage of this measure is that it is dimensionless hence comparable across categories and it avoids scaling effects we show that in the logit model with arbitrary heterogeneity in brand preferences and price sensitivities the absolute cross price effect is symmetric we develop an econometric model for simultaneously estimating the asymmetric and neighborhood price effects and assess their relative strengths we also estimate two alternate models that address the following questions i if i were managing the ith highest priced brand which brand do i impact the most by discounting and which brand hurts me the most through price discounts ii who hurts whom in national brand vs store brand competition based on a meta analysis of 1 060 cross price effects on 280 brands from 19 different grocery product categories we provide the following empirical generalizations 1 the asymmetric price effect holds with cross price elasticities but tends to disappear with absolute cross price effects 2 the neighborhood price effect holds with both cross price elasticities and absolute cross price effects and is significantly stronger than the asymmetric price effect on both measures of cross price effects 3 a brand is affected the most by discounts of its immediately higher priced brand followed closely by discounts of its immediately lower priced brand 4 national brands impact store brands more so than the reverse when the cross effect is measured in elasticities but the asymmetric effect does not hold with absolute effects store brands hurt and are in turn hurt the most by the lower priced national brands that are adjacent in price to the store brands 5 cross price effects are greater when there are fewer competing brands in the product category and among brands in nonfood household products than among brands in food products the implications of these findings are discussed

modeling asymmetric competition the effects of the marketing actions of one brand can be distributed among its competitors market shares in a complex manner this paper presents and illustrates methods for modeling brand competition and brand strategies in markets where competitive effects can be differentially and asymmetrically distributed we discuss the empirical specification parameter estimation and competitive strategy implications of the models proposed price and advertising competition among eleven brands of an australian household product is used to illustrate the application of these procedures

empirical generalizations about market evolution and stationarity we present empirical generalizations about conditions under which marketing variables evolve or remain stationary we first define evolution statistically and make the case why it is an important concept for increasing our understanding of long run marketing effectiveness we then briefly review ways in which evolution can be tested empirically from readily available data we present a database of over 400 prior analyses and catalog the relative incidence of stationarity versus evolution in market performance and marketing spending we find that evolution is the dominant characteristic for sales and marketing mix spending but that stationarity is the dominant characteristic for market share thus we find strong support for the conjecture that many markets are in a long run equilibrium where the relative position of the players is only temporarily disturbed by their respective marketing activities we assess the impact of a number of covariates on the likelihood of finding stationarity evolution in sales

a duopolistic model of dynamic competitive advertising abstract this paper proposes a differential game model of competitive advertising decisions for non durable products by extending the lanchester model and the deal model of competitive advertising in the literature the proposed model is compared empirically with the lanchester model for model fitting and forecast accuracy it is shown that the model is suitable for an actual market and out performs the lanchester model in forecast accuracy the model provides a sensible modeling alternative to the lanchester model for the study of dynamic competitive advertising decisions necessary and sufficient conditions for open loop and closed loop nash equilibrium solutions to the model are discussed a numerical algorithm for open loop and closed loop nash strategies to the model is developed

the rational effect of price promotions on sales and consumption we explore the rational effect of price variation on sales and consumption in markets where consumers are uncertain about the future price of goods we first derive an optimal ordering policy which expresses the amount a consumer should purchase and consume in a given period as a function of the observed price of the good the distribution of future prices and the nature of his or her inventory this policy extends previous normative models of inventory control such as those by golabi 1985 and kalymon 1970 to the case where the amount to consume in a given period is an explicit decision variable and prices follow a first order stochastic process we then use this model to explore how changes in the long run frequency and temporal correlations of price promotions should normatively affect the contemporaneous relationship between purchase consumption and price among the predictions which follow from the model are that consumption should rationally increase with the size of existing inventories the short term sensitivity of sales to prices should be greater than that of consumption to price and this discrepancy increases with decreases in the temporal correlation of price deals and the long term relative frequency of price deals

the persistence of marketing effects on sales are marketing efforts able to affect long term trends in sales or other performance measures answering this question is essential for the creation of marketing strategies that deliver a sustainable competitive advantage this paper introduces persistence modeling to derive long term marketing effectiveness from time series observations on sales and marketing expenditures first we use unit root tests to determine whether sales are stable or evolving trending over time if they are evolving we examine how strong this evolution is univariate persistence and to what extent it can be related to marketing activity multivariate persistence an empirical example on sales and media spending for a chain of home improvement stores reveals that some but not all advertising has strong trend setting effects on sales we argue that traditional modeling approaches would not pick up these effects and therefore seriously underestimate the long term effectiveness of advertising the paper concludes with an agenda for future empirical research on long run marketing effectiveness

models of health plan choice this paper considers alternative approaches to accounting for consumer heterogeneity in econometric models of health plan choice in particular we compare and contrast approaches used by health economists and marketing researchers to explicitly allow for consumer heterogeneity in assessment of plan provider quality and characteristics as a result we are able to identify conditions under which approaches utilized by health economists are preferred over those utilized by marketing researchers and vice versa for example we find that in the absence of data on prior year choice which is often the case of models estimated in the health economics literature it would be valuable to estimate random coefficient models which have not been estimated in such works and in the presence of data on prior year choice which is often the case of models estimated in the marketing literature a model wherein consumer characteristics simply interact with plan specific constants and premium and which has not been estimated in that literature offers better fits than random coefficient semi parametric random coefficient and latent class models which have been previously estimated in that literature the model offers important managerial insights useful for targeting benefits of various plans to different customer segments

market boundaries and product choice illustrating attraction and substitution effects what happens to the share of choices each item receives when the choice set boundaries are extended by adding a new item that is extremely good on one dimension but poor on the others first there is a substitution effect whereby the new item takes choice share mainly from similar items in the set second there is an attraction effect resulting in a general shift of preference toward the added item experimental studies show that choice patterns conflict with current theoretical and common sense ideas about the effect of added alternatives on choice

analysis of global bifurcations in a market share attraction model in this paper we demonstrate how the global dynamics of an economic model can be analyzed in particular as an application we consider a market share attraction model widely used in the analysis of interbrand competition in marketing theory we analyze the local and global dynamic properties of the resulting two dimensional noninvertible dynamical system in discrete time the main result of this paper is given by the study of some global bifurcations that change the structure of the attractors and their basins these bifurcations are investigated by the use of critical curves a powerful tool for the analysis of the global properties of noninvertible two dimensional maps 2000 elsevier science b v all rights reserved jel classixcation e32 m30

a two stage sales forecasting procedure using discounted least squares the authors develop a two stage forecasting methodology for estimating the sales responses to marketing and environmental variables when it is likely that their impacts will change unpredictably over time the methodology is based on an integrated least squares procedure that uses regression analysis in stage 1 to estimate the coefficients of the controllable and environmental variables in combination with a stage 2 discounted least squares smoothing procedure that updates key parameters in response to changing market conditions the effectiveness of the methodology is demonstrated by applying it to weekly sales data from a major retail chain

using game theory to model competition the article is an exposition of the basic concepts of noncooperative game theory and their application to advertising product and price competition

a unified approach to identifying estimating and testing demand structures with aggregate scanner data a one to one map between a specific demand structure and a restricted cross elasticity matrix is developed and tested using a random utility model the resulting demand structure can be used to evaluate a firm s ability to differentiate its products and can help determine if demand is characterized by factors that are easy to change similar brands are assumed to share common attributes that are stochastically evaluated by the consumer resulting in a random utility model with correlated errors the map results in more precise cross elasticity estimates and can be used to both identify and test possible structures

pricing strategies in a dynamic duopoly a differential game model we formulate a differential game model for dynamic pricing in a duopolistic market firms demand functions are derived from utility maximizing behavior of consumers with the demand for a brand given by the logit model preferences for brands are assumed to evolve over time in the market in a manner akin to learning models postulated in the marketing literature we derive the differential equations governing the equilibrium open loop price paths over time and show that in steady state the brand with the higher preference level charges the higher price the formulation is extended to include the effects of consumer heterogeneity and equilibrium steady state prices are compared with those obtained when heterogeneity is ignored a comparison of steady state dynamic prices with myopic prices is provided an empirical example is discussed to show how steady state model predictions may be obtained from actual longitudinal purchase data

misspecification of capital asset pricing this study documents empirical anomalies which suggest that either the simple one period capital asset pricing model capm is misspecified or that capital markets are inefficient in particular portfolios based on firm size or earnings price e p ratios experience average returns systematically different from those predicted by the capm furthermore the abnormal returns persist for at least two years this persistence reduces the likelihood that these results are being generated by a market inefficiency rather the evidence seems to indicate that the equilibrium pricing model is misspecified however the data also reveals that an e p effect does not emerge after returns are controlled for the firm size effect the firm size effect largely subsumes the e p effect thus while the e p anomaly and value anomaly exist when each variable is considered separately the two anomalies seem to be related to the same set of missing factors and these factors appear to be more closely associated with firm size than e p ratios

technical note simplified estimation procedures for mci models structural transformations of the mci model are presented which make the model easily estimated using dummy variables with widely available regression packages the mci model is empirically shown to provide better predictive power than several other models of similar form but ones which do not produce logically consistent market share estimates

a multiattribute model of consumer choice during product learning the processes of consumer preference formation during product learning are analyzed a hypothesis about how individuals form attribute expectations is used to derive a dynamic multinomial logit model of individual choice which endogenously recognizes product learning the model and its underlying assumptions are then tested in the context of an interactive grocery store learning game the results support most elements of the proposed model structure an assumption of temporal stationarity in attribute salience however could not be supported approaches to implementation of the model are discussed and implications for marketing management and research in individual choice modeling are addressed

labor market segmentation and the determination of wages in the public private formal and informal sectors in san jose costa rica a striking feature of many cities in less developed countries ldcs is the coexistence of large well organized high technology firms with the small street vendors who own little but a wooden box to sit on this apparent dualism in the urban economy has been a concern of students of economic development for many years several international agencies notably the international labour organisation ilo and the world bank have focused attention on this phenomenon the ilo popularized the terms formal sector and informal sector to describe this dichotomy to many economists one consequence of this dualism is labor market segmentation labor market segmentation plays a crucial role in explanations provided for some important issues such as rural urban migration urban poverty unemployment underemployment and growth 2 in this article i examine the hypothesis that labor market segmentation exists in san jos6 costa rica between the public and private formal sectors and between the privateformal and informal sectors defined in the appendix i define labor market segmentation as a situation where because of institutional barriers to occupational mobility between sectors a worker in the lower sector has less than full access to a job in the upper sector held by an observationally identical worker 3 if there were no barriers workers in the low wage sector would enter the high wage sector and force the wages in that sector down until wages across sectors were equalized that is labor market segmentation implies differences in wages for observationally identical workers relying on this inference most of the empirical literature on labor market segmen

estimating a multinomial probit model of brand choice using the method of simulated moments the multinomial probit model of brand choice is theoretically appealing for marketing applications as it is free from the independence of irrelevant alternatives property of the multinomial logit model however difficulties in estimation have restricted its widespread use in marketing this paper presents an application of the method of simulated moments a new methodology that enables easy estimation of probit models with a large number of alternatives in the choice set we describe the theoretical development of the technique and using pseudo simulated data conduct numerical experiments to compare the method with existing techniques for estimating probit models using the scanner panel data on the purchases of catsup we provide an empirical application of the method of simulated moments to the estimation of the parameters of a multinomial probit model estimating the covariance structure associated with the underlying latent variable probit model enables us to identify broad patterns of similarities across alternatives it also enables us to derive a pairwise similarity matrix across choice alternatives which when input into a multi dimensional scaling routine provides us with a graphical representation of competitive structure in the catsup market for completeness we compare the substantive implications for the effects of marketing variables obtained from the multinomial probit model with those obtained from models in the extant marketing literature

price induced patterns of competition this research focuses on how price changes influence the observed pattern of brand competition the paper begins with a basic utility model formulation and examines the implications of three major classes of preference distributions on the expected patterns of competition a price tier model is proposed to operationalize the theory and to allow predictive testing the price tier model is estimated on 28 brands across four product categories the results show a specific asymmetric pattern of price competition higher price higher quality brands steal share from other brands in the same price quality tier as well as from brands in the tier below however lower price lower quality brands take sales from their own tier and the tier below brands but do not steal significant share from the tiers above the results are consistent with a bimodal preference distribution with the regular price indifference point being located toward the lower quality end of the preference distribution for the categories analyzed

estimating demand heterogeneity using aggregated data an application to the frozen pizza category this paper combines different aggregate level data sets to identify new product demand in consumer packaged goods cpg categories our approach augments market level time series data with widely available summaries of household purchase behavior i e brand penetration and purchase set size data we show that this augmentation is helpful in the estimation of consumer heterogeneity for instance observing a brand with relatively large shares and low penetration typically indicates that preferences are dispersed with relatively few customers liking the brand a lot whereas the combination of share and penetration is informative about heterogeneity with realistic sample sizes in isolation neither variable may lead to precise estimates of heterogeneity in addition other widely available data e g category penetration is helpful in estimating the size of the total market using a large monte carlo study the paper demonstrates the benefits of the proposed approach in estimating model parameters price elasticities and brand switching empirically the approach is used to evaluate the launch of a new national brand digiorno in the frozen pizza category the new brand is inferred to be very successful at expanding the category while avoiding cannibalization of existing company share using only standard information i e market shares to estimate the demand model leads in our data to poor estimates of the degree of consumer taste variation and of switching to a new brand

competition under generalized attraction models applications to quality competition under yield uncertainty we characterize the equilibrium behavior in a broad class of competition models in which the competing firms market shares are given by an attraction model and the aggregate sales in the industry depend on the aggregate attraction value according to a general function each firm s revenues and costs are proportional with its expected sales volume with a cost rate that depends on the firm s chosen attraction value according to an arbitrary increasing function whereas most existing competition papers with attraction models can be viewed as special cases of this general model we apply our general results to a new set of quality competition models here an industry has n suppliers of a given product who compete for the business of one or more buyers each of the suppliers encounters an uncertain yield factor with a given general yield distribution the buyers face uncertain demands over the course of a given sales season the suppliers compete by selecting key characteristics of their yield distributions either their means their standard deviations or both these choices have implications for their per unit cost rates

market models and heteroscedasticity of residual security returns bickel s tests provide attractive robust alternatives to traditional tests of heteroscedasticity nyse securities have homoscedastic residuals once nonnormality of security returns is allowed some portfolio designs may generate some heteroscedastic residuals but this heteroscedasticity is reduced by the kraus litzenberger quadratic market model this result suggests a misspecification in the traditional market model

advertising strategies in a dynamic oligopoly the author uses a dynamic model of oligopolistic advertising competition in which competitors are assumed to make a series of single period advertising decisions with salvage values attached to achieved sales in each period as the foundation for empirical analysis of the competitive situation involving the three largest ready to eat cereal manufacturers kellogg general mills and the post division of philip morris general foods the primary insight of the author s empirical analysis is that general mills places a higher future value on achieved sales than do the other competitors in the market

modeling multiple sources of heterogeneity in multinomial logit models methodological and managerial issues we offer a framework to specify and estimate various sources of heterogeneity in multinomial logit brand choice models we let each brand specific intercept and each parameter of the explanatory variable vector vary randomly across households in addition we distinguish loyal households from the rest our results suggest that incorporating multiple sources of heterogeneity improves the model fit and suggests higher impact of marketing mix elements on brand choice we highlight the importance of incorporating multiple sources of heterogeneity the model we implement yields valuable managerial insights

segmented or competitive labour markets a normal roy model with four sectors is developed it allows to derive tests of several assumptions on the working of the labor market strongly or weakly competitive or segmented it shows that more important a feature of labor markets than segmentation is the presence of comparative advantages for individuals between the various economic sectors the model is applied to data on women s labor force participation in the main towns of colombia in 1980 it uses multivariate probit and tobit techniques copyright 1991 by the econometric society

breeding competitive strategies we show how genetic algorithms can be used to evolve strategies in oligopolistic markets characterized by asymmetric competition the approach is illustrated using scanner tracking data of brand actions in a real market an asymmetric market share model and a category volume model are combined to represent market response to the actions of brand managers the actions available to each artificial brand manager are constrained to four typical marketing actions of each from the historical data each brand s strategies evolve through simulations of repeated interactions in a virtual market using the estimated weekly profits of each brand as measures of its fitness for the genetic algorithm the artificial agents bred in this environment outperform the historical actions of brand managers in the real market the implications of these findings for the study of marketing strategy are discussed

mobility and the return to education testing a roy model with multiple markets self selected migration presents one potential explanation for why observed returns to a college education in local labor markets vary widely even though u s workers are highly mobile to assess the impact of self selection on estimated returns this paper first develops a roy model of mobility and earnings where workers choose in which of the 50 states plus the district of columbia to live and work available estimation methods are either infeasible for a selection model with so many alternatives or place potentially severe restrictions on earnings and the selection process this paper develops an alternative econometric methodology that combines lee s 1983 parametric maximum order statistic approach to reduce the dimensionality of the error terms with more recent work on semiparametric estimation of selection models e g ahn and powell 1993 the resulting semiparametric correction is easy to implement and can be adapted to a variety of other polychotomous choice problems the empirical work which uses 1990 u s census data confirms the role of comparative advantage in mobility decisions the results suggest that self selection of higher educated individuals to states with higher returns to education generally leads to upward biases in ols estimates of the returns to education in state specific labor markets while the estimated returns to a college education are significantly biased correcting for the bias does not narrow the range of returns across states consistent with the finding that the corrected return to a college education differs across the u s the relative state to state migration flows of college versus high school educated individuals respond strongly to differences in the return to education and amenities across states

market information and firm performance the value of new information depends on how accurate the information is but it may also depend on the characteristics of the firm and the nature of the industry it operates in we develop a game theoretic model to understand how firm and industry characteristics moderate the effect of market information on firm profits our results suggest that information is more valuable when product substitutability is higher suggesting that information is of greater value in more competitive industries our results also suggest that although industry size does not affect the value of information information is more valuable for larger firms we find that except under some conditions more precise market information has a greater impact on profits in a stackelberg mode of conduct than in a bertrand nash mode

allocating spending between advertising and information technology in electronic retailing this study examines coordination issues that occur in allocating spending between advertising and information technology it in electronic retailing electronic retailers run the risk of overspending on advertising to attract customers but underspending on it thus resulting in inadequate processing capacity at the firm s website in this paper we present a centralized joint marketing it model to optimally allocate spending between advertising and it and we discuss an uncoordinated case where marketing and it make suboptimal advertising and capacity decisions we show how these decisions can be coordinated either by reducing the value of a customer session or by designing an optimal processing contract between marketing and it both the coordination methods can be implemented with only local knowledge of the it function yet they generate a solution that almost matches the quality of the centralized solution we extend our basic model to consider demand uncertainty lagged advertising effects and uncertainties in the lead time to acquire it capacity with demand uncertainty electronic retailers should reduce spending on advertising and increase it capacity if there is potential for a demand upswing and the cost of it capacity is relatively low the value of a customer session should be further reduced when uncertainties exist this is required to share the risk of excess or inadequate it capacity

derivation of covariance probit elasticities the full covariance probit model is highly regarded due to the flexibility with which it can represent cross brand effects explicit formulae for these cross brand effects for the general n brand case have never appeared in print nor have the direct elasticities for the model this note fills that omission

semiparametric versus parametric classification models an application to direct marketing in this paper we are concerned with estimation of a classification model using semiparametric and parametric methods benefits and limitations of semiparametric models in general and of manski s maximum score method in particular are discussed the maximum score method yields consistent estimates under very weak distributional assumptions the maximum score method can very easily be used in situations where it is mare serious to make one kind of classification error than another in this paper we use a so called threshold crossing model to discriminate between credit card holders and nonholders the estimated parameters of the logit model differ significantly from the estimates of maximum score given an loss function maximum score performs better than the logit model

dynamic effects of the order of entry on market share trial penetration and repeat purchases for frequently purchased consumer goods a time series cross sectional analysis of 18 successful later entrants in 8 categories of consumer packaged goods over the period from october 1983 to january 1988 confirms previous empirical findings that after correcting for differences in marketing effort later entrants suffer a long term market share disadvantage new evidence of the penalties associated with later entry are found in statistical estimation of models of cumulative trial first repeat and subsequent repeat purchasing significantly lower asymptotic levels are found in both trial and repeat behavior however based on this data the rate of approach of later entrants to their lower asymptotic performance measures is either equal to or faster than early entrants and provides evidence of a compensating partial effect accrued by later entrants

formal choice models in marketing the paper gives an overview and evaluates the theoretical traditions underlying choice models that are used in marketing in particular the emphasis of this essay is on the underlying assumptions limitations and empirical demands of these choice models four fundamental choice models are used as a basis to analyze this complex field the neoclassical economic theory as extended by lancaster the risk preference theory of choices under uncertainty the strict utility theory and the random utility theory these four choice models and their extensions are compared and contrasted along the three critical steps in the model building process theory generation parameterization and estimation

competitive reactions to advertising and promotion attacks how do competitors react to each other s price promotion and advertising attacks what are the reasons for the observed reaction behavior we answer these questions by performing a large scale empirical study on the short run and long run reactions to promotion and advertising shocks in over 400 consumer product categories over a four year time span our results clearly show that the most predominant form of competitive response is passive in nature when a reaction does occur it is usually retaliatory in the same instrument i e promotion attacks are countered with promotions and advertising attacks are countered with advertising there are very few long run consequences of any type of reaction behavior by linking reaction behavior to both cross and own effectiveness we further demonstrate that passive behavior is often a sound strategy while firms that do opt to retaliate often use ineffective instruments resulting in spoiled arms accommodating behavior is observed in only a minority of cases and often results in a missed sales opportunity when promotional support is reduced the ultimate impact of most promotion and advertising campaigns depends primarily on the nature of consumer response not the vigilance of competitors

reply reflections on the cost of simplifying preference models author s reply to comments by johnson johnson r m 1986 commentary marketing sci 5 322 and greenberg greenberg m g 1986 commentary marketing sci 5 320 321 about this paper hagerty m r 1986 the cost of simplifying preference models marketing sci 5 298 319

the use of linear logit models in marketing research the author discusses the use of the linear logit model in marketing research a brief review of the linear logit model focuses on model formulation estimation evaluation and inference procedures

tests of market models heteroskedasticity or misspecification abstract this paper investigates the nature and the incidence of heteroskedasticity and misspecification in the market models by utilizing tests that are generally applicable the results show that heteroskedasticity appears more frequently than misspecification even though both are serious problems the evidence also indicates that the use of a quadratic market model or equally weighted market returns may lead to a smaller percentage of heteroskedastic cases but that in general this advantage has to be offset against an increase in the occurrence of specification errors small firms and january returns are also observed to produce a higher incidence of both heteroskedasticity and misspecification

chapter 6 market share models publisher summary this chapter describes that three basic principles motivate the specification of the market share models market share models should be competitive descriptive as well as predictive and profit oriented being fundamentally competitive implies that one cannot know the effect or effectiveness of a marketing action without accounting for the actions of competitors market share models are models for understanding how the marketing efforts of every brand impact the results in a competitive marketplace only by describing the influence of each marketing instrument can one gain a basis for marketing planning prediction alone is not enough time series models that forecast the future from the past sales provide no insight into how sales are generated the emphasis on being descriptive also embraces the need to understand the areas in which consumer choice probabilities are synonymous with market shares as well part of the goal of description transcends what can be done by market share models alone managers need to understand that their efforts have potentially competitive effects and potentially market expansive effects in sales response models these effects are comingled but by combining descriptive market share models for the competitive effects with descriptive category volume models for the market expansive effects managers obtain a much richer understanding of the market the profit oriented goal of market share analysis urges us to ask how the firm s allocations of resources to aspects of the marketing mix produce bottom line results

empirical analysis of closed loop duopoly advertising strategies closed loop perfect equilibria in a lanchester duopoly differential game of advertising competition are used as the basis for empirical investigation two systems of simultaneous nonlinear equations are formed one from a general lanchester model and one from a constrained model two empirical applications are conducted in one involving coca cola and pepsi cola a formal statistical testing procedure is used to detect whether closed loop equilibrium advertising strategies are used by the competitors rather than open loop strategies in the second application involving anheuser busch and miller the general model is estimated results indicate that closed loop equilibria better explain dynamic advertising competition than do open loop equilibria also closed loop equilibrium advertising strategies implied by model estimates show that competitive advertising levels may or may not be monotonic in market share

commercial use of upc scanner data industry and academic perspectives the authors report the findings from an exploratory investigation of the use of upc scanner data in the consumer packaged goods industry in the u s the study examines the practitioner community s view of the use of scanner data and compares these views with academic research forty one executives from ten data suppliers packaged goods manufacturers and consulting firms participated in wide ranging in person interviews conducted by the authors the interviews sought to uncover key questions practitioners would like to answer with scanner data how scanner data is applied to these questions and the industry s perspective regarding the success that the use of scanner data has had in each area the authors then compare and contrast practitioners views regarding the resolution of each issue with academic research this produces a 2 2 classification of each question as resolved or unresolved from the perspectives of industry and academia along the diagonal of the 2 2 issues viewed as unresolved by both groups are important topics for future research issues deemed resolved by both groups are correspondingly of lower priority in the off diagonal cells industry and academics disagree these topics should be given priority for discussion information exchange and possible further research practitioners reported that scanner data analysis has had the most success and been most widely adopted for decision making in consumer promotions i e coupons trade promotions and pricing for example logit and regression models applied to scanner data have revealed very low average consumer response to coupons which has directly led to reduced couponing activity managers also reported high levels of comfort with and impact from analyses of trade promotions and price elasticities while industry views most of the issues in these areas to be resolved academic research raises concerns about a number of practices in common commercial use these include price threshold analysis and trade promotion evaluation using baseline and incremental sales in product strategy advertising and distribution management practitioners reported that the use of scanner data has had more limited development success and impact in the case of new product decisions scanner data use has been slow to develop due to the inherent limitations of historicaldata for these decisions and a heavy reliance on traditional primary research methods in advertising scanner data is widely analyzed with models but confusion among practitioners is very high due to controversies about methods e g what level of data aggregation is best and conflicting results in distribution and retail management scanner data use has tremendous potential but a mixed track record to date thus practitioners view the use of scanner data as unresolved for most issues in product strategy advertising and distribution this view is largely though not entirely consistent with academic research which has only begun to address many of the key questions raised by practitioners in light of the large number of unresolved issues and mixed record of scanner data use to date the authors offer aseries of specific recommendations for immediate and long term research priorities that are likely to have the greatest impact on commercial utilization of upc scanner data topics of immediate priority include price thresholds and gaps baseline and incremental sales base price elasticity competitive reactions measurement of advertising effects management of brand equity rationalization of product assortments and category management long term priorities include a greater emphasis on profitability versus sales or market share developing prescriptive models versus descriptive models and the need for industry standards

chapter 9 econometric and time series market response models publisher summary marketing has seen a rapid expansion in the widespread use of quantitative methods correlation and regression analysis were among the first techniques used as marketing research emerged as a discipline after world war ii in the early 1970s regression analysis became econometrics simultaneous equation systems could be estimated almost as easily as single regression equations while econometrics as a whole continues to flourish as new and more sophisticated estimation techniques and associated computer software have become available simultaneous equation systems have not become widely prevalent the dynamic structure of marketing variables themselves is addressed in the chapter followed by discussions of leads and lags among marketing variables and the assessment of the direction of causality dynamic properties of sales response functions have been discussed in more detail marketing generalizations that have been uncovered as well as empirical evidence on the shape of the sales response function is reported

an investigation of the labor market earnings of panamanian males evaluating sources of inequality this paper presents empirical evidence on the determinants of labor market earnings and inequality for males in panama using newly available microdata we estimate earnings equations based on the measurement framework of mincer 1974 and compare them with those for other countries at various stages of economic development we present evidence on two aspects of inequality in less developed economies labor market segmentation and social stratification we present tests of the segmentation hypothesis including several of the dual labor market hypotheses and discuss their inherent ambiguity we also present evidence on the importance of family background for earnings determination and educational attainment

an empirical investigation of advertising strategies in a dynamic duopoly the equilibrium profit maximizing advertising policies of firms operating in a dynamic duopoly are derived by linking in a single framework the econometric estimation of the market response function and the technique of differential games that characterizes dynamic competitive behavior we use the lanchester model of combat to represent the system dynamics that capture the competitive shifts due to investments in advertising by the two market rivals we determine the equilibrium advertising levels using both closed and open loop policies we also compare these equilibrium advertising policies for each firm to those obtained using an optimal control theory formulation wherein the advertising spending levels of the rival are assumed to be known the empirical results obtained by analyzing the advertising rivalry between coke and pepsi for the period 1968 1981 under the above three alternative spending policies provide some interesting insights into the nature of competition between these two market rivals a significant contribution of this paper is to extend the existing literature on advertising competition by integrating theoretical and empirical analyses

predictive testing of consumer choice models not subject to independence of irrelevant alternatives the probabilistic modeling of the relationship between objective or perceived characteristics of multiattribute alternatives and consumer choice is receiving increased attention in marketing and ot

the impact of capital structure on advertising competition an empirical study this article examines the interaction between capital structure and advertising competition using a sample of firms that raise significant amounts of capital we find that firms whose financial leverage has decreased as a result of their new funding increase their advertising significantly more than firms whose leverage has increased we also find that these firms industry rivals respond less aggressively with their own advertising when they have more debt in their capital structure overall our results support the view that financial leverage has a dampening effect on the intensity with which a firm chooses to compete in the product market

using discrete choice models with experimental design data to forecast consumer demand for a unique cultural event an approach is developed to forecast participation in unique events with long gestation periods experimental observations of choice are derived for conjoint measurement type multiattribute alternatives that describe possible event configurations the choice data are analyzed by means of discrete choice econometric models a multinomial logit choice model is applied to forecast the choice of attendance at various types of international expositions the empirical work was part of the planning efforts undertaken to investigate the potential demand for an international exposition to be held in eastern australia in conjunction with the australian 1988 bicentennial celebrations

quality of higher education and the labor market in developing countries evidence from an education reform in senegal summary while many studies examine the effect of primary education quality on labor market outcomes in developing countries little is known about the effects at higher levels we exploit the quasi experiment provided by a large scale education reform launched in senegal in 2000 to investigate how quality improvements at the university level affect employment our difference in difference estimates suggest that young high skilled workers experienced a nine percentage point employment gain relative to older workers they are also more likely to have better jobs in the service industry or government suggesting a reduction in the mismatch between the quality of high skilled labor demanded and supplied

perceptual position and competitive brand strategy in a two dimensional two brand market brand positioning and competitive reaction are important determinants of optimal brand strategy analyses of brand strategy have focused on optimal pricing and positioning issues using either empirical models of perceptions and preferences game theory to examine competition or both however the important issues of advertising and distribution strategy have not been fully addressed this paper analyzes competition and strategy between two brands that compete in a two dimensional market with advertising and distribution spending in addition to prices and product positions in particular for a unimodal taste distribution of ideal points we show how optimal competitive nash equilibrium marketing mix levels and profits depend on the positions of both brands brands can reposition to increase profit and under what conditions these strategies imply minimum versus maximum differentiation positioning equilibria and how the intensity of advertising and distribution competition affect equilibrium brand positions

long run substitutability between more and less educated workers evidence from u s states 1950 1990 we estimate the aggregate long run elasticity of substitution between more educated workers and less educated workers the slope of the inverse demand curve for more relative to less educated workers at the u s state level our data come from the five 1950 1990 decennial censuses our empirical approach allows for state and time fixed effects and relies on time and state dependent child labor and compulsory school attendance laws as instruments for endogenous changes in the relative supply of more educated workers we find the aggregate long run elasticity of substitution between more and less educated workers to be around 1 5

endogeneity and heterogeneity in a probit demand model estimation using aggregate data two issues that have become increasingly important while estimating the parameters of aggregate demand functions to study firm behavior are theendogeneity of marketing activities typically price andheterogeneity across consumers in the market under consideration ignoring these issues in the estimation of the demand function parameters can lead to biased and inconsistent estimates for the effects of marketing activities endogeneity and heterogeneity have achieved prominence in large measure because of the increasing popularity of logit models to characterize demand functions usingaggregate data the logit model accounts for purchase incidence and brand choice by including a no purchase alternative in the consumer s choice set this allows for category sales to change as a function of the marketing activities of brands in the category there are three issues with using the logit model with the no purchase option to characterize demand when studying competitive interactions among firms 1 the marketing literature dealing with brand choice behavior at the consumer level has found that the iia restriction is not appropriate as each brand in the choice set is more similar to some brands than it is to others 2 studies have found that the purchase incidence decision is distinct from the brand choice decision hence it may not be appropriate to model the no purchase decision as just another alternative in the choice set with the iia restriction holding across all brands and the no purchase option 3 even if the distinction between the purchase incidence and brand choice decisions is accounted for via for example a nested logit specification accounting for the purchase incidence decision with aggregate data requires assumptions for computing the share of the no purchase alternative which is otherwise unobserved in this paper we propose a probit model as an alternative to the logit model to specify the aggregate demand functions of firms competing in oligopoly markets the probit model avoids the iia property that affects the logit model at the individual consumer level furthermore the probit model can naturally account for the distinction between the purchase incidence and brand choice decisions due to the general covariance structure assumed for the utilities of the alternatives we demonstrate how the parameters of the proposed model can be estimated using aggregate time series data from a product market in the estimation we account for the endogeneity of marketing variables as well as for heterogeneity across consumers our results indicate that both endogeneity as well as heterogeneity need to be accounted for even after allowing for a non iia specification at the individual consumer level specific to our data we also find that ignoring endogeneity has a bigger impact on the estimated price elasticities than ignoring the effects of heterogeneity a comparison of the elasticities obtained from the probit model with those from the corresponding logit specification indicates that therange of elasticities obtained from the probit model across brands is larger than that obtained from the logit the results have implications for issues such as firm level pricing in addition to specifying a probit model and providing comparisons with the logit model the paper also addresses the third issue raised above we propose a simple alternative to the purchase incidence brand choice specification by decomposing the demand for a brand into a category demand equation and a conditional brand choice share equation we provide a comparison of results from this specification to those from the specification that includes the no purchase alternative and find that estimated elasticities are sensitive to the specification used we also estimate the demand function parameters using a traditional specification such as the double logarithmic model here we find that the estimated elasticities could be signed in such a manner as to be not useful for firm level pricing decisions one of the key limitations of the proposed model is that while it accounts for the purchase incidence and brand choice decisions of households it does not account for differences across consumers in their purchase quantities the model and analysis are best suited for product categories in which consumers typically make single unit purchases another limitation is more practical in nature while recent advances have been made in computing probit probabilities it could nevertheless be a challenge to do so when the number of alternatives is large

evidence of heteroscedasticity and mis specification issues in the market model results from the athens stock exchange the traditional tests and the relevant explanations given by researchers on the basis of their empirical results in cases where there is evidence of heteroscedasticity and surrounding mis specification issues in the market model is investigated and criticized to this purpose data from the athens stock exchange are used to get meaningful comparisons and results the authors first apply the classical heteroscedasticity and mis specification tests used in the literature by researchers and analyse the results also under a classical view they then apply more recent and efficient tests to find out contradictions and disproportions between the former and the latter tests as well as to draw comments and conclusions supplementary to the existing evidence and to propose other appropriate ways for estimation and specification of the market model it appears as a general conculsion of the authors work that singnificant distortions are observed in the traditional market model when it is used in small but con