Eric Greenleaf - Academia.edu (original) (raw)
Papers by Eric Greenleaf
Social Science Research Network, 2006
Social Science Research Network, 2008
... Eric A. Greenleaf Stern School of Business, New York University, New York, NY 10012, egreenle... more ... Eric A. Greenleaf Stern School of Business, New York University, New York, NY 10012, egreenle@stern.nyu.edu Page 2. ... price, higher quality brands versus lower price, lower quality brands (Blattberg and Wisniewski 1989). ...
Journal of Marketing Research, May 1, 1992
The author examines whether the response styles of yeasaying and standard deviation in rating sca... more The author examines whether the response styles of yeasaying and standard deviation in rating scale responses convey information on respondents' attitudes or create bias that distorts attitude information and marketing research. A method is proposed to identify attitude information components and bias components in response styles, using prediction errors in attitude-behavior models. Analysis of data from a large-scale consumer survey supports the presence of both attitude information and bias components in standard deviation, and an attitude information but not a bias component in yeasaying. This finding suggests that correcting rating scale data by removing the bias but not the attitude information in standard deviation can increase the accuracy of survey research. Examples are given of how bias in standard deviation, and the scoring correction, affect segmentation research.
Marketing Science, Feb 1, 1995
This paper investigates the impact of reference price effects on retailer price promotions and de... more This paper investigates the impact of reference price effects on retailer price promotions and describes why these effects can make promoting profitable. First, we analyze the profit impact of reference price effects generated by a single period of promotion. The promotion can increase profit if the gain that these effects create in the promotion period outweighs the loss they create in future periods. We then describe how retailers can estimate the optimal strategy of recurring promotions that maximizes profits from reference price effects over a time horizon. Examples of such strategies are presented for a retailer selling a national brand of peanut butter. We obtain insights into how promotion prices, timing, and profits are affected by changes in costs, interest rates, consumers' reactions to reference price effects, and error in estimates used in the model. The retailer's optimal reaction to a trade deal is also examined. This strategy involves a phase of increased promotion activity sandwiched between phases of decreased activity. We explain these results using the effects described in the single-period model.
... An example is the plant photographs taken by the English photographer Charles Jones (ca. 1895... more ... An example is the plant photographs taken by the English photographer Charles Jones (ca. 1895–1910; Sexton & Johnson, 1998). ... Many highly respected movie direc-tors, such as Ingmar Bergman and Woody Allen, made movies in black Page 281. ...
Social Science Research Network, 2009
In the past two decades, pricing research has paid increasing attention to instances where a prod... more In the past two decades, pricing research has paid increasing attention to instances where a product's price is divided into a base price and one or more mandatory surcharges, a practice termed partitioned pricing. Recently, partitioned pricing strategies in the marketplace have become more pervasive and complex, raising concerns that consumers do not always fully attend to or process all price information, and underestimate total prices, which in turn influences their purchasing behavior. Thus, understanding how partitioned prices affect consumers is of increasing interest to consumer researchers, public policy makers, and marketing managers. This paper reviews and organizes the academic literature on partitioned pricing and proposes an agenda for future research. We focus on the psychological processes underlying partitioned pricing, to help these three constituencies understand how partitioned pricing works, the mechanisms by which it exerts its impact, and the appropriate areas where the practice may need regulation to protect consumers.
Management Science, Sep 1, 1993
The multimillion dollar price guarantees that an auction house can offer for paintings have alrea... more The multimillion dollar price guarantees that an auction house can offer for paintings have already had a large impact on auction house profits, and place new demands on the auctioneer's decision making and negotiating skills. Yet auctioneers have not been studied as independent entities and decision makers. To create a price guarantee, the auction house and the seller must negotiate both the guarantee amount and the extra commission the seller pays if the auction price exceeds the guarantee. We present a normative model of negotiations and find the frontier of guarantee and commission that is the Nash bargaining solution. We also determine the optimal reserve that the auctioneer should place on guaranteed property. We find that guarantees decrease the auction house's expected revenue compared to a conventional auction, but do allow it to attract business which might otherwise be lost. Guarantees benefit sellers, increasing the expected value and lowering the variance of their auction revenue. The auctioneer's optimal strategy depends not only on the distribution of the artwork's auction price, but also the price it will bring if it fails to sell at auction. In the latter case the auction house must pay the seller the guarantee and then sell the artwork, which it now owns, in a private secondary market where buyers regard the property as “damaged goods” and lower their offers. Although all points on the frontier produce equal expected revenue, several frequently used decision making rules suggest that both parties may prefer a guarantee arrangement where the seller pays no additional commission and the guarantee has the lowest value on the frontier.
ACR North American Advances, 2014
Journal of Consumer Research, Sep 1, 1995
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC-BY) license 4.0
Management Science, Dec 1, 2002
Please scroll down for article-it is on subsequent pages With 12,500 members from nearly 90 count... more Please scroll down for article-it is on subsequent pages With 12,500 members from nearly 90 countries, INFORMS is the largest international association of operations research (O.R.) and analytics professionals and students. INFORMS provides unique networking and learning opportunities for individual professionals, and organizations of all types and sizes, to better understand and use O.R. and analytics tools and methods to transform strategic visions and achieve better outcomes. For more information on INFORMS, its publications, membership, or meetings visit http://www.informs.org
Social Science Research Network, 1998
ABSTRACT
Journal of Consumer Research, Sep 1, 2004
Studies have shown that users experience regret in online electronic auctions. Our study adds to ... more Studies have shown that users experience regret in online electronic auctions. Our study adds to the research on the antecedents of regret by examining the effects of the major types of auction design on users' experience of regret. Towards this goal, we analyzed bidders' experience of regret in English and Dutch auctions. Given that English and Dutch auctions are known to produce different types of bidding behavior and outcomes, we expect that the two types of auction design will also have a differential impact on experiencing regret. We report results from a lab experiment that was implemented as a self-developed mobile application for hotel room reservations. We examined the effects of the two open-bid auction types on the experience of regret, and found that users are more likely to experience regret in Dutch auctions. We point out the theoretical relevance and practical implications of our findings.
Journal of Consumer Psychology, 2016
In the past two decades, pricing research has paid increasing attention to instances where a prod... more In the past two decades, pricing research has paid increasing attention to instances where a product's price is divided into a base price and one or more mandatory surcharges, a practice termed partitioned pricing. Recently, partitioned pricing strategies in the marketplace have become more pervasive and complex, raising concerns that consumers do not always fully attend to or process all price information, and underestimate total prices, which in turn influences their purchasing behavior. Thus, understanding how partitioned prices affect consumers is of increasing interest to consumer researchers, public policy makers, and marketing managers. This paper reviews and organizes the academic literature on partitioned pricing and proposes an agenda for future research. We focus on the psychological processes underlying partitioned pricing, to help these three constituencies understand how partitioned pricing works, the mechanisms by which it exerts its impact, and the appropriate areas where the practice may need regulation to protect consumers.
Journal of Consumer Research, Sep 1, 1984
... consumer behavior that includes leisure activities (Unger and Kernan 1983), hobbies (Bloch an... more ... consumer behavior that includes leisure activities (Unger and Kernan 1983), hobbies (Bloch and Bruce 1984), creativity (Hirschman 1983), games (Huizinga 1938 ... Similarly, Csikszentmihalyi (1975) has explored the phenomenology of play in what he calls "flow experiences . . . ...
Management Science, Apr 1, 1996
Most auction sellers consign property to auction houses rather than holding the auction themselve... more Most auction sellers consign property to auction houses rather than holding the auction themselves. In addition to charging sellers a commission on property that sells in the auction, many auction houses also specify buy-in penalties in auction contracts. This is an amount the seller must pay the auction house if the property fails to sell at auction. An important managerial question for auction houses is whether and when buy-in penalties can increase revenues of the auction house, seller, or both, and what combinations of commission and buy-in penalty to use. We show that auctions which combine buy-in penalties with lower commissions Pareto-dominate auctions that use only commissions. This strategy motivates the seller to set a lower reserve, which creates a surplus in auction revenues that can go to one or both parties. This strategy is Pareto-dominant even if the auction house and the seller are uncertain about the number of bidders at the auction, or the auction house is uncertain about the seller's own valuation for the property, at the time the buy-in penalty, commission, and reserve are contractually set. We also discuss the incentive issues raised by this strategy.
Empirical Studies of The Arts, 1986
Models of evaluative judgment in applied aesthetics generally assume that movements of objects&am... more Models of evaluative judgment in applied aesthetics generally assume that movements of objects' positions in a multidimensional perceptual space will produce corresponding changes in preferences. However, such spatial representations have usually been tested using static designs or, at best, longitudinal studies that fail to tie perceptual movements to shifts in affective response. This study reports what we believe to be a first dynamic analysis of changes in aesthetic responses. Specifically, twenty-nine aesthetically naive subjects supplied perceptual and affective ratings of twenty art prints on four occasions spaced a week apart. Multiple discriminant analysis (MDA) of the perception data created an MDA space representing each person's perceptions of each print at the beginning and end of the period. We then constructed each individual's preference function based on the MDA space, used beginning and ending perceived positions to compute changes in that preference function, regarded these as predictions of changes in actual affect, and correlated predicted with actual affective shifts to obtain a validity assessment of about r2 = .25 for our dynamic spatial analysis of trends in tastes.
Journal of Marketing Research, Nov 1, 1998
Many firms divide a product's price into two mandatory parts, such as the base price of a mail-or... more Many firms divide a product's price into two mandatory parts, such as the base price of a mail-order shirt and the surcharge for shipping and handling, rather than charging a combined, all-inclusive price. The authors call this strategy partitioned pricing. Although firms presumably use partitioned pricing to increase demand and profits, there is little clear empirical support that these prices increase demand or any theoretical explanation for why this should occur. The authors test hypotheses of how consumers process partitioned prices and how partitioned pricing affects consumers' processing and recall of total costs and their purchase intentions and certain types of demand. The results suggest that partitioned prices decrease consumers'• recalled total costs and increase their demand. The manner in which the surcharge is presented and consumers' affect for the brand name also influence how they react to partitioned prices.
Public Opinion Quarterly, 1992
Research on extreme response style (ERS) in rating scale responses has been characterized by conf... more Research on extreme response style (ERS) in rating scale responses has been characterized by conflicting findings and little agreement over how to assemble and validate ERS mea- sures. This article proposes that, when ERS is defined as a pro- portion of extreme responses, an ERS measure will be more ac- curate if the items are uncorrelated and have equal extreme response proportions. Furthermore, appropriate stochastic mod- els should be used to assess the internal reliability and convergent validity of these measures. An ERS measure is created and vali- dated with this method, using items from a survey administered in 1975 and 1987 to large samples of U.S. adults serving on a consumer panel. We find that ERS is stable over a lengthy survey compared to a benchmark stability for a "perfect" measure. Fur- thermore, the distribution of ERS over this population is stable over time. Respondents' ERS is related to their age, education level, and household income but not to their gender.
This paper proposes to measure the impact of promotional messages sent during an online auction, ... more This paper proposes to measure the impact of promotional messages sent during an online auction, on the final price of this auction. We model this impact through a disaggregated and dynamic model. This model simultaneously takes into account the following three factors: (i) the direct impact of marketing messages on the auction price when messages affect bidders' valuations, (ii) the indirect impact of messages on this price when messages attract new bidders to the auction, and (iii) the possibility that the auctioneer's strategy for sending messages may depend on bidding activity, the number of bidders, and the current auction price. Results, based on online auctions organised by the French airline company Air France, show the indirect influence of promotional messages on the final auction price (measured by sequence of bids), through the entry of new bidders in the auction.
Auctioneers often issue promotional messages during auctions conducted live and online. We propos... more Auctioneers often issue promotional messages during auctions conducted live and online. We propose and test a model of the impact of these messages on final auction prices. The model examines messages’ direct price impact, which affects valuations of existing bidders, and their indirect price impact, through the two mediators of affecting new bidder entry and jump bidding. This model also examines how the auctioneer’s message-sending decisions are influenced by past bidding and past message-sending in the auction. We create sub-models of these bidder and auctioneer decisions, which allow dynamic auction decisions that change at each bid (for bidders) or bid interval (for the auctioneer), and link these sub-models to a sub-model of the final auction price. We also distinguish between informational messages that convey information about the item’s attributes and bidding messages that focus on bidder actions particular to auctions. The proposed model is supported when tested on data from real time Internet auctions of Air France airline tickets. A counterfactual analysis provides insights into how changing the frequency or placement of messages can increase or decrease the predicted auction price.
Social Science Research Network, 2006
Social Science Research Network, 2008
... Eric A. Greenleaf Stern School of Business, New York University, New York, NY 10012, egreenle... more ... Eric A. Greenleaf Stern School of Business, New York University, New York, NY 10012, egreenle@stern.nyu.edu Page 2. ... price, higher quality brands versus lower price, lower quality brands (Blattberg and Wisniewski 1989). ...
Journal of Marketing Research, May 1, 1992
The author examines whether the response styles of yeasaying and standard deviation in rating sca... more The author examines whether the response styles of yeasaying and standard deviation in rating scale responses convey information on respondents' attitudes or create bias that distorts attitude information and marketing research. A method is proposed to identify attitude information components and bias components in response styles, using prediction errors in attitude-behavior models. Analysis of data from a large-scale consumer survey supports the presence of both attitude information and bias components in standard deviation, and an attitude information but not a bias component in yeasaying. This finding suggests that correcting rating scale data by removing the bias but not the attitude information in standard deviation can increase the accuracy of survey research. Examples are given of how bias in standard deviation, and the scoring correction, affect segmentation research.
Marketing Science, Feb 1, 1995
This paper investigates the impact of reference price effects on retailer price promotions and de... more This paper investigates the impact of reference price effects on retailer price promotions and describes why these effects can make promoting profitable. First, we analyze the profit impact of reference price effects generated by a single period of promotion. The promotion can increase profit if the gain that these effects create in the promotion period outweighs the loss they create in future periods. We then describe how retailers can estimate the optimal strategy of recurring promotions that maximizes profits from reference price effects over a time horizon. Examples of such strategies are presented for a retailer selling a national brand of peanut butter. We obtain insights into how promotion prices, timing, and profits are affected by changes in costs, interest rates, consumers' reactions to reference price effects, and error in estimates used in the model. The retailer's optimal reaction to a trade deal is also examined. This strategy involves a phase of increased promotion activity sandwiched between phases of decreased activity. We explain these results using the effects described in the single-period model.
... An example is the plant photographs taken by the English photographer Charles Jones (ca. 1895... more ... An example is the plant photographs taken by the English photographer Charles Jones (ca. 1895–1910; Sexton & Johnson, 1998). ... Many highly respected movie direc-tors, such as Ingmar Bergman and Woody Allen, made movies in black Page 281. ...
Social Science Research Network, 2009
In the past two decades, pricing research has paid increasing attention to instances where a prod... more In the past two decades, pricing research has paid increasing attention to instances where a product's price is divided into a base price and one or more mandatory surcharges, a practice termed partitioned pricing. Recently, partitioned pricing strategies in the marketplace have become more pervasive and complex, raising concerns that consumers do not always fully attend to or process all price information, and underestimate total prices, which in turn influences their purchasing behavior. Thus, understanding how partitioned prices affect consumers is of increasing interest to consumer researchers, public policy makers, and marketing managers. This paper reviews and organizes the academic literature on partitioned pricing and proposes an agenda for future research. We focus on the psychological processes underlying partitioned pricing, to help these three constituencies understand how partitioned pricing works, the mechanisms by which it exerts its impact, and the appropriate areas where the practice may need regulation to protect consumers.
Management Science, Sep 1, 1993
The multimillion dollar price guarantees that an auction house can offer for paintings have alrea... more The multimillion dollar price guarantees that an auction house can offer for paintings have already had a large impact on auction house profits, and place new demands on the auctioneer's decision making and negotiating skills. Yet auctioneers have not been studied as independent entities and decision makers. To create a price guarantee, the auction house and the seller must negotiate both the guarantee amount and the extra commission the seller pays if the auction price exceeds the guarantee. We present a normative model of negotiations and find the frontier of guarantee and commission that is the Nash bargaining solution. We also determine the optimal reserve that the auctioneer should place on guaranteed property. We find that guarantees decrease the auction house's expected revenue compared to a conventional auction, but do allow it to attract business which might otherwise be lost. Guarantees benefit sellers, increasing the expected value and lowering the variance of their auction revenue. The auctioneer's optimal strategy depends not only on the distribution of the artwork's auction price, but also the price it will bring if it fails to sell at auction. In the latter case the auction house must pay the seller the guarantee and then sell the artwork, which it now owns, in a private secondary market where buyers regard the property as “damaged goods” and lower their offers. Although all points on the frontier produce equal expected revenue, several frequently used decision making rules suggest that both parties may prefer a guarantee arrangement where the seller pays no additional commission and the guarantee has the lowest value on the frontier.
ACR North American Advances, 2014
Journal of Consumer Research, Sep 1, 1995
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC-BY) license 4.0
Management Science, Dec 1, 2002
Please scroll down for article-it is on subsequent pages With 12,500 members from nearly 90 count... more Please scroll down for article-it is on subsequent pages With 12,500 members from nearly 90 countries, INFORMS is the largest international association of operations research (O.R.) and analytics professionals and students. INFORMS provides unique networking and learning opportunities for individual professionals, and organizations of all types and sizes, to better understand and use O.R. and analytics tools and methods to transform strategic visions and achieve better outcomes. For more information on INFORMS, its publications, membership, or meetings visit http://www.informs.org
Social Science Research Network, 1998
ABSTRACT
Journal of Consumer Research, Sep 1, 2004
Studies have shown that users experience regret in online electronic auctions. Our study adds to ... more Studies have shown that users experience regret in online electronic auctions. Our study adds to the research on the antecedents of regret by examining the effects of the major types of auction design on users' experience of regret. Towards this goal, we analyzed bidders' experience of regret in English and Dutch auctions. Given that English and Dutch auctions are known to produce different types of bidding behavior and outcomes, we expect that the two types of auction design will also have a differential impact on experiencing regret. We report results from a lab experiment that was implemented as a self-developed mobile application for hotel room reservations. We examined the effects of the two open-bid auction types on the experience of regret, and found that users are more likely to experience regret in Dutch auctions. We point out the theoretical relevance and practical implications of our findings.
Journal of Consumer Psychology, 2016
In the past two decades, pricing research has paid increasing attention to instances where a prod... more In the past two decades, pricing research has paid increasing attention to instances where a product's price is divided into a base price and one or more mandatory surcharges, a practice termed partitioned pricing. Recently, partitioned pricing strategies in the marketplace have become more pervasive and complex, raising concerns that consumers do not always fully attend to or process all price information, and underestimate total prices, which in turn influences their purchasing behavior. Thus, understanding how partitioned prices affect consumers is of increasing interest to consumer researchers, public policy makers, and marketing managers. This paper reviews and organizes the academic literature on partitioned pricing and proposes an agenda for future research. We focus on the psychological processes underlying partitioned pricing, to help these three constituencies understand how partitioned pricing works, the mechanisms by which it exerts its impact, and the appropriate areas where the practice may need regulation to protect consumers.
Journal of Consumer Research, Sep 1, 1984
... consumer behavior that includes leisure activities (Unger and Kernan 1983), hobbies (Bloch an... more ... consumer behavior that includes leisure activities (Unger and Kernan 1983), hobbies (Bloch and Bruce 1984), creativity (Hirschman 1983), games (Huizinga 1938 ... Similarly, Csikszentmihalyi (1975) has explored the phenomenology of play in what he calls "flow experiences . . . ...
Management Science, Apr 1, 1996
Most auction sellers consign property to auction houses rather than holding the auction themselve... more Most auction sellers consign property to auction houses rather than holding the auction themselves. In addition to charging sellers a commission on property that sells in the auction, many auction houses also specify buy-in penalties in auction contracts. This is an amount the seller must pay the auction house if the property fails to sell at auction. An important managerial question for auction houses is whether and when buy-in penalties can increase revenues of the auction house, seller, or both, and what combinations of commission and buy-in penalty to use. We show that auctions which combine buy-in penalties with lower commissions Pareto-dominate auctions that use only commissions. This strategy motivates the seller to set a lower reserve, which creates a surplus in auction revenues that can go to one or both parties. This strategy is Pareto-dominant even if the auction house and the seller are uncertain about the number of bidders at the auction, or the auction house is uncertain about the seller's own valuation for the property, at the time the buy-in penalty, commission, and reserve are contractually set. We also discuss the incentive issues raised by this strategy.
Empirical Studies of The Arts, 1986
Models of evaluative judgment in applied aesthetics generally assume that movements of objects&am... more Models of evaluative judgment in applied aesthetics generally assume that movements of objects' positions in a multidimensional perceptual space will produce corresponding changes in preferences. However, such spatial representations have usually been tested using static designs or, at best, longitudinal studies that fail to tie perceptual movements to shifts in affective response. This study reports what we believe to be a first dynamic analysis of changes in aesthetic responses. Specifically, twenty-nine aesthetically naive subjects supplied perceptual and affective ratings of twenty art prints on four occasions spaced a week apart. Multiple discriminant analysis (MDA) of the perception data created an MDA space representing each person's perceptions of each print at the beginning and end of the period. We then constructed each individual's preference function based on the MDA space, used beginning and ending perceived positions to compute changes in that preference function, regarded these as predictions of changes in actual affect, and correlated predicted with actual affective shifts to obtain a validity assessment of about r2 = .25 for our dynamic spatial analysis of trends in tastes.
Journal of Marketing Research, Nov 1, 1998
Many firms divide a product's price into two mandatory parts, such as the base price of a mail-or... more Many firms divide a product's price into two mandatory parts, such as the base price of a mail-order shirt and the surcharge for shipping and handling, rather than charging a combined, all-inclusive price. The authors call this strategy partitioned pricing. Although firms presumably use partitioned pricing to increase demand and profits, there is little clear empirical support that these prices increase demand or any theoretical explanation for why this should occur. The authors test hypotheses of how consumers process partitioned prices and how partitioned pricing affects consumers' processing and recall of total costs and their purchase intentions and certain types of demand. The results suggest that partitioned prices decrease consumers'• recalled total costs and increase their demand. The manner in which the surcharge is presented and consumers' affect for the brand name also influence how they react to partitioned prices.
Public Opinion Quarterly, 1992
Research on extreme response style (ERS) in rating scale responses has been characterized by conf... more Research on extreme response style (ERS) in rating scale responses has been characterized by conflicting findings and little agreement over how to assemble and validate ERS mea- sures. This article proposes that, when ERS is defined as a pro- portion of extreme responses, an ERS measure will be more ac- curate if the items are uncorrelated and have equal extreme response proportions. Furthermore, appropriate stochastic mod- els should be used to assess the internal reliability and convergent validity of these measures. An ERS measure is created and vali- dated with this method, using items from a survey administered in 1975 and 1987 to large samples of U.S. adults serving on a consumer panel. We find that ERS is stable over a lengthy survey compared to a benchmark stability for a "perfect" measure. Fur- thermore, the distribution of ERS over this population is stable over time. Respondents' ERS is related to their age, education level, and household income but not to their gender.
This paper proposes to measure the impact of promotional messages sent during an online auction, ... more This paper proposes to measure the impact of promotional messages sent during an online auction, on the final price of this auction. We model this impact through a disaggregated and dynamic model. This model simultaneously takes into account the following three factors: (i) the direct impact of marketing messages on the auction price when messages affect bidders' valuations, (ii) the indirect impact of messages on this price when messages attract new bidders to the auction, and (iii) the possibility that the auctioneer's strategy for sending messages may depend on bidding activity, the number of bidders, and the current auction price. Results, based on online auctions organised by the French airline company Air France, show the indirect influence of promotional messages on the final auction price (measured by sequence of bids), through the entry of new bidders in the auction.
Auctioneers often issue promotional messages during auctions conducted live and online. We propos... more Auctioneers often issue promotional messages during auctions conducted live and online. We propose and test a model of the impact of these messages on final auction prices. The model examines messages’ direct price impact, which affects valuations of existing bidders, and their indirect price impact, through the two mediators of affecting new bidder entry and jump bidding. This model also examines how the auctioneer’s message-sending decisions are influenced by past bidding and past message-sending in the auction. We create sub-models of these bidder and auctioneer decisions, which allow dynamic auction decisions that change at each bid (for bidders) or bid interval (for the auctioneer), and link these sub-models to a sub-model of the final auction price. We also distinguish between informational messages that convey information about the item’s attributes and bidding messages that focus on bidder actions particular to auctions. The proposed model is supported when tested on data from real time Internet auctions of Air France airline tickets. A counterfactual analysis provides insights into how changing the frequency or placement of messages can increase or decrease the predicted auction price.