Annotated Bibliography on Marketing Margins for Agricultural and Food
Products with Emphasis on Specialty Crops
June 2012
Prepared by John Bovay
This research was funded by California Department of Food and Agriculture,
Specialty Crop Block Grant Program (SCBGP) Grant CFDA# 10.170: “Measuring and
Understanding the Pattern of Margins between Farm and Retail Prices for California
Specialty Crops to Increase Growers Returns”
List of research Reports, Papers and Articles
Frederick V. Waugh, 1934. “Margins in Marketing.” Journal of Farm Economics, Vol.
16, No. 2, pp. 233-245.
In one of the first papers on the topic, Waugh discussed the measurement of
marketing margins and the changes in margins over time. He suggested that the
study of efficiency in marketing may be even more important than the study of
production efficiency, and that the problem might require a dynamic explanation, a
precedent for Wohlgenant (1985). He noted problems in gathering data, e.g., that
the heterogeneity in cuts of beef and in dairy products makes determination of the
farm-retail spread for beef and milk difficult. He also dealt with the regulation of
marketing, writing that any regulatory limitation of competition should result in
lower consumer prices, higher producer prices, or both.
Bruce L. Gardner, 1975. “The Farm-Retail Price Spread in a Competitive Food
Industry.” American Journal of Agricultural Economics, Vol. 57, No. 3, pp. 399-409.
In his paper on the farm-retail price spread in a competitive industry, Bruce Gardner
developed a model to explain equilibria observed in the retail food, farm output, and
marketing sectors. The primary focus of the paper is how the price spread responds
to shifts in demand, farm supply, or the demand or supply of marketing inputs. He
noted the importance of substitution within the marketing sector, which implies in a
change of prices for both farm inputs and non-farm inputs when demand for food
increases or supply of farm inputs increases. His conclusions are broad: no simple
markup pricing rule can accurately represent the farm-retail price spread, because
shifts may occur in any of the three sectors. He showed that (a) the effect of demand
shifts on the retail-farm price ratio depends on the relative elasticity of supply of
farm products and marketing inputs; (b) increased supply of farm products
increases the ratio; (c) increased supply of marketing inputs decreases the ratio. He
also derived results regarding the response of the price ratio to price ceilings and
floors, and results that depend on the value of the elasticities of farm and retail
demand and on the elasticity of substitution.
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Dale M. Heien, 1980. “Markup Pricing in a Dynamic Model of the Food Industry.”
American Journal of Agricultural Economics, Vol. 62, No. 1, pp. 10-18.
Developed a dynamic model of farm and retail pricing. Tested the hypothesis that
price changes are transmitted from wholesale-to-retail using 24 commodities.
Among produce commodities, the results supported the hypothesis for oranges,
frozen orange juice, potatoes, and frozen French fries; the results suggested
bidirectional causality for fresh orange juice and canned tomatoes; and they
suggested independence between wholesale and retail prices for eggs, apples,
tomatoes, and lettuce.
Ronald W. Ward, 1982. “Asymmetry in Retail, Wholesale, and Shipping Point Pricing
for Fresh Vegetables.” American Journal of Agricultural Economics, Vol. 64, No. 2, pp.
205-212.
Analyzed price linkages in fresh vegetables between retail, wholesale, and shipping
point. Tested the hypothesis that there should be strong linkages between the three
points, because fresh vegetables require minimal processing. He found that both
retail and shipping point prices generally lagged wholesale prices, and offered the
hypothesis that wholesale markets were more concentrated as the explanation.
Further, he tested for asymmetry in price transmission from wholesale to retail and
shipping point and found that retail prices tended to respond more quickly to
wholesale price increases than to decreases. (The asymmetry was observed in
celery, cabbage, corn, green peppers, potatoes, and tomatoes, while symmetry was
observed only in carrots and cucumbers.) Finally, he found that the farm-retail price
spread had widened over time.
Michael K. Wohlgenant, 1985. “Competitive Storage, Rational Expectations, and
Short- Run Food Price Determination.” American Journal of Agricultural Economics,
Vol. 67, No. 4, pp. 739-748.
To explain farm-retail price spreads and price stickiness for food commodities,
Wohlgenant developed a dynamic model in which producers derive price
expectations according to the rational expectations hypothesis, and applied the
model to estimate the implications of inventories on price spreads. In this model,
the short-run market rental rate depends on anticipated gains or losses from
holding inventories; that is, on the next period’s expected retail prices. Inventory
costs consist of both (1) the physical costs of holding inventory, which increase with
inventory; and (2) the costs of set-up and stocking out, which decline as inventory
rises, for a given sales rate. Producers maximize the expected present discounted
value of net revenue. He concluded that the estimating equation for retail price
depends on the nature of the stochastic process by which next period’s wholesale
price is determined. He also noted that by including overidentifying restrictions in
his model, he could test the rational expectations hypothesis, and disentangle the
effects of realized price from the effects of realized price on farm-retail price
spreads.
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Michael K. Wohlgenant and John D. Mullen, 1987. “Modeling the Farm-Retail Price
Spread for Beef.” Western Journal of Agricultural Economics, Vol. 12, No. 2, pp. 119125.
The authors used a relative price spread model, in which the price spread is
calculated only relative to the industry output price and marketing input price, both
deflated by the retail price. As Gardner (1975) noted, the common approach is to
assume that price spread is determined as a combination of proportional and
absolute markups, but this only works if shocks affect either supply or demand, and
not both simultaneously. Wohlgenant and Mullen tested the relative price spread
model using an application to beef, and showed that it performed better,
empirically, than the common markup approach.
J.S. Shonkwiler and T.G. Taylor, 1988. “Food Processor Price Behavior: Firm-Level
Evidence of Sticky Prices.” American Journal of Agricultural Economics, Vol. 70, No. 2,
pp. 239-244.
Used an empirical friction model to show that the indirect costs of changing prices,
for a major processor of frozen, concentrated orange juice, caused price rigidity.
Found that prices are equally rigid in response to increases and decreases in
indirect costs.
Michael K. Wohlgenant, 1989. “Demand for Farm Output in a Complete System of
Demand Functions.” American Journal of Agricultural Economics, Vol. 71, No. 2, pp.
241-252.
Developed a new conceptual and empirical framework on retail-to-farm demand
linkages. He showed that, except for fresh fruit, increases in retail demand are
positively related to both retail and farm prices. These results are consistent with
constant-returns-to-scale production technology. For two categories, (1) fresh fruits
and (2) processed fruits and vegetables, he argued that the empirical results likely
do not match the model prediction because of problems in aggregating such
heterogeneous products into a single commodity. Even if Wohlgenant had obtained
reliable results for fruits and vegetables, we would want disaggregated results for
fruit and vegetables to use in any study focused on the price-retail spread of fruits
and vegetables.
Daniel H. Pick, Jeffrey Karrenbrock, and Hoy F. Carman, 1990. “Price Asymmetry and
Marketing Margin Behavior: An Example for California—Arizona Citrus.”
Agribusiness, Vol. 6, No. 1, pp. 75-84.
Estimated the extent and timing of retail price changes for lemons and Navel
oranges in response to changes in FOB price. Also estimated changes in marketing
margins, which the authors expected to increase in response to increases in FOB
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price. Employed a method similar to Heien (1980) and Ward (1982). First, they
determined that for lemons, the retail price was more volatile than the FOB price;
however, there was no similar relationship that held for oranges across all four
markets studied. For lemons, the authors found that retail markets responded more
to FOB increases than decreases in two of the four markets, and could not reject
symmetric response in the other two markets. For oranges, three markets showed
asymmetric responses to FOB price increases and one showed a symmetric
response. About one of the four markets (depending on the test) showed the
expected response of marketing margins to FOB price changes. Finally, they
conclude that there was a direct relationship between responsiveness of retail price
to FOB price changes and responsiveness of marketing margins to FOB price
changes.
Garth J. Holloway, 1991. “The Farm-Retail Price Spread in an Imperfectly
Competitive Food Industry.” American Journal of Agricultural Economics, Vol. 73, No.
4, pp. 979-989.
Used the model of Gardner (1975) to test for perfect competition in food industries.
He failed to reject the hypothesis that food marketing sectors, including eggs, fresh
fruits, fresh vegetables, and processed fruits and vegetables, are perfectly
competitive on the basis of the price spreads in those industries.
Henry W. Kinnucan and Robert G. Nelson, 1993. “Vertical Control and the FarmRetail Price Spread for Eggs.” Review of Agricultural Economics, Vol. 15, No. 3, pp.
473-482.
Examined whether increased vertical control in the egg industry hurts welfare,
because market power enables price markups, or helps welfare through increased
farm-to-retail co- ordination (i.e., efficiency in the marketing sector). Over the
period 1973-1983, the farm-retail price spread decreased by 42% as vertical
control—contracts and vertical integration—increased. Using OLS and modeling
production technology as constant-returns-to-scale, the authors found a highly
significant negative relationship between price spread and vertical control, and
concluded that vertical control improves welfare because of improved coordination.
This is in the context of a product with fixed-proportions technology, with very little
processing between farmgate and retail. They estimated that 58% of the decrease in
price spread is attributable to increased vertical control. Thus, their result is
consistent with the results of Holloway (1991): vertical control is not anticompetitive. They do not use any variation in quality (considering only large Grade
A eggs); but they do use variation in seasonality on a quarterly basis.
Oral Capps, Jr., Patrick J. Byrne, and Gary W. Williams, 1995. “Analysis of Marketing
Margins in the U.S. Lamb Industry.” Agricultural and Resource Economics Review, Vol.
24, Issue 2, pp. 232-240.
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Showed that in the lamb industry, increases in packer market power (as measured
by the four-firm concentration index) had a positive effect on farm-retail price
spreads. Augmented the relative price spread method of Wohlgenant and Mullen
(1987).
Nicholas J. Powers, 1995. “Sticky Short-Run Prices and Vertical Pricing: Evidence
from the Market for Iceberg Lettuce.” Agribusiness, Vol. 11, No. 1, pp. 57-75.
Used the approach of Heien (1980) to examine the transmission of price changes in
California iceberg lettuce, from farmgate to wholesale to retail. Found that the
response of wholesale prices to FOB prices was symmetric (to increases and
decreases), that the price changes fully passed through, and responses were also
symmetric to trucking cost changes. Found that retail prices responded more slowly
to wholesale price changes than wholesale prices responded to FOB price changes.
Retail prices responded at least as fast, and with greater magnitude, to increases in
wholesale prices than to decreases, but the price changes exhibited only partial
pass-through. Finally, the author simulated the effects of offering constant FOB price
for a month, and found that the consumer price should be lower under such a buyer
policy.
Richard J. Sexton and Mingxia Zhang, 1996. “A Model of Price Determination for
Fresh Produce with Application to California Iceberg Lettuce.” American Journal of
Agricultural Economics, Vol. 78, No. 4, pp. 924-934.
Modeled the short-run determination of farm prices for fresh produce that has inelastic short-run supply, with an empirical application to the iceberg lettuce
industry in California. They characterize the industry as one in which there is
imperfect competition in procurement, meaning that supply and demand do not
determine a unique price and that monopsonistic buyers may extract surplus. They
employed a switching regression frame- work, in which wholesale price is set equal
to harvest cost at some times, and set above harvest cost at some value depending
on the bargaining power of buyers. Under perfect competition, farmers would
receive all existing rents, and Sexton and Zhang tested the null hypothesis that
farmers’ bargaining power was inversely related to the volume of lettuce on the
market. They rejected both the hypotheses that the wholesale market was perfectly
competitive and that it is collusive; they found that, 30% of the time, the crop was
sold at the harvest cost, and that the remainder of the time, the crop was sold at a
marked-up price.
Michael K. Wohlgenant, 2001. “Marketing Margins: Empirical Analysis.” Chapter 16
in Handbook of Agricultural Economics, Volume 1. B. Gardner and G. Rausser, eds.
Elsevier Science B.V.
In this Handbook chapter, Wohlgenant wrote that marketing margins have attracted
much public scrutiny, but little consensus. Among the questions commonly asked
are: Are they too large? How have they changed? What variation is systematically
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explicable? How do they relate to market power? What is the incidence of marketing
costs on retail and farm prices? What is the transmission for shocks to marketing
costs to reach retail and farm prices? Does the concentration of middlemen help or
hurt farmers? In the chapter, Wohlgenant addressed determinants of marketing
margins, and modeling them in the context of fixed and variable proportions and
markup pricing, concluding that none of these modeling approaches works
perfectly. He also discussed lags in food price determination, with particular
attention to the model of Wohlgenant (1985) in which any direction of changes in
price spreads is theoretically possible.
Timothy J. Richards and Paul M. Patterson, 2003. “Competition in Fresh Produce
Markets: An Empirical Analysis of Marketing Channel Performance.” USDA-ERS
Contractor and Cooperator Report No. 1.
This paper analyzed retailers’ ability to set noncompetitive prices in fresh apples,
table grapes, fresh California oranges, and Florida grapefruits. Similar to Sexton and
Zhang (1996), this analysis employed a switching regression framework. They
showed that retail prices for semi-perishable fresh produce are mostly determined
at the shipping point; that retail prices respond more rapidly to wholesale price
increases than to decreases; and that retail prices are fixed relative to shipper
prices, indicating that retailers possess bargaining power and control over prices.
They also found evidence of tacit collusion, using an econometric specification
developed by Green and Porter (1984). Their tests showed that retailers exhibit
market power in both buying and selling of fresh apples and grapefruit, and market
power in the sale of fresh oranges. Finally, they showed that retailer power falls as
the quantity of commodity sold increases.
Richard Sexton, Mingxia Zhang, and James Chalfant, 2003. “Grocery Retailer
Behavior in the Procurement and Sale of Perishable Fresh Produce.” USDA-ERS
Contractor and Cooperator Report No. 2.
In this publication, the authors applied the model of Sexton and Zhang (1996) to
new industries, tested for changes in farm-retail spread as a function of production
volume and shipping costs, and tested for any overall trends in farm-retail spread in
these industries. Under perfect competition, the variations in the spread would be
fully explained by variations in sellers’ marginal cost. Under competition, an
increase in volume should decrease the farm-retail spread, if an increased volume
gives sellers more bargaining power. On the other hand, if the spread increases as a
function of volume, then buyers are acting as oligopsonists. They conclude that, in
the California and Arizona iceberg lettuce and fresh tomato industries, there is
strong evidence that increases in marketed volume increase the farm-retail price
spread, and that, in Florida, a high degree of industry coordination helps protect
mature-green tomato growers from price fluctuations. Further, they found that
retail chains tended to stabilize retail prices, a strategy that reduces total surplus
and therefore farm-sector income. Inelastic demands for produce, driven partly
because consumers are unwilling to shop at multiple grocery stores, enables retail
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markups over marginal cost, and harms upstream producer welfare. Finally, they
find that there is no consistent relationship between the prices of bagged iceberg
salads and the farmgate price of iceberg lettuce.
Julian M. Alston, Daniel A. Sumner, and Stephen A. Vosti, 2006. “Are Agricultural
Policies Making Us Fat? Likely Links between Agricultural Policies and Human
Nutrition and Obesity, and Their Policy Implications.” Review of Agricultural
Economics Vol. 28, No. 3, pp. 313–322.
Showed that over 1960–2003, there has been a clear downward trend in commodity
prices, with an exception in beef cattle, which has had several temporary price
increases. Over somewhat shorter periods within 1960–2003 for which data are
available, the farmgate price of tomatoes, broccoli, potatoes, and apples fell
significantly, while the farmgate price of lettuce, asparagus, and table grapes
increased; oranges showed no trend after 1970. Meanwhile, the authors showed
that consumer prices for food had no strong relationship with farm prices. Part of
the lack of correlation was attributed to quality improvements not seen in the data,
such as improved packaging or processing, and also to increased seasonal
availability of items such as strawberries. These quality improvements cannot be
easily measured, so changes in marketing margins for fresh fruits and vegetables
over time are also difficult to estimate.
Hayden Stewart, 2006. “How Low Has the Farm Share of Retail Food Prices Really
Fallen?” USDA-ERS Economic Research Report Number 24.
Conventional analysis showed that the farm share of the consumer’s food dollar, in
produce, decreased from 34% to 19% for fresh vegetables and from 33% to 20% for
fresh fruits over 1982–2004. However, the conventional analysis is problematic
because it uses the same basket of goods in 1982 and 2004. Stewart revised this
analysis using the current basket of goods, and showed that the farm share of the
consumer’s food dollar is somewhat higher than the conventional analysis, but still
lower than in 1982: 23.5% for fresh vegetables and 26.6% for fresh fruits.
Ephraim Leibtag, 2006. “The Impact of Big-Box Stores on Retail Food Prices and the
Consumer Price Index.” USDA-ERS Economic Research Report Number 33.
Explored the effects of the expansion of big-box retailers on retail food prices. While
the price of food has increased annually by less than 3% per year (according to the
CPI), prices at any one point in time vary by approximately 10% across store
formats, i.e., between conventional supermarkets and big-box retailers such as WalMart, Target, and Costco. Leibtag showed that previous price comparisons across
store formats overestimated the price difference, by not controlling for differences
in package-size or quality. In an earlier paper, Hausman and Leibtag showed that, by
not accounting for a shift in store formats from conventional supermarkets to bigbox retailers, the CPI overestimated the inflation rate by up to 15%. This study
improved estimates further, by accounting for variation in package weight, using
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ACNielsen Homescan data. He showed that less-processed products show more
variation in prices, and argued that entry of big-box stores forces other retailers to
lower prices. Overall, he concluded that consumer welfare increased because of the
entry of big-box stores, but did draw conclusions about producer (farmer) welfare.
Fred Kuchler and Hayden Stewart, 2008. “Price Trends Are Similar for Fruits,
Vegetables, and Snack Foods.” USDA-ERS Economic Research Report Number 55.
This paper built on Alston, Sumner, and Vosti (2006). The authors selected 11 fresh
pro- duce commodities for which there has been relatively little change in quality
over the period analyzed (1980–2006, for six commodities, and a shorter period for
five other commodities). They showed that for 9 of 11 fresh produce commodities
considered, the consumer price fell by 0.5–1.6% per year. For the other two
commodities, broccoli and field-grown tomatoes, there was significant change in
processing (e.g., broccoli florets) and in technology and product attributes (for fieldgrown tomatoes) over the period. The authors also discussed how produce
departments in grocery stores nearly doubled the number of SKUs available over
1987–1997, and consumers tended to spend more on partially-processed products
at the end of the period.
Sunil P. Dhoubhadel, Sergio C. Castillo, and Oral Capps, Jr., 2009. “Analysis of
Marketing Margins under Food Recalls and BSE Outbreaks in the U.S. Beef Industry.”
Selected Paper prepared for presentation at the Agricultural & Applied Economics
Associations 2009 AAEA & ACCI Joint Meeting, Milwaukee, WI, July 26-28.
Found that BSE announcements in the USA and Canada increase marketing margins,
whereas recalls do not increase farm-to-retail margins. Severe recalls do have a
positive effect on marketing margins from farm-to-wholesale, but decrease the
margin from wholesale-to-retail. Used the augmented relative price spread method
of Capps et al. (1995).
Timothy J. Richards, Ram Acharya, and Ignacio Molina, 2009. “Retail and Wholesale
Market Power in Organic Foods.” Selected Paper prepared for presentation at the
Agricultural & Applied Economics Association 2009 AAEA & ACCI Joint Annual
Meeting, Milwaukee, Wisconsin, July 26-29.
Showed that the supply of organic apples is limited by the standards that must be
met to attain organic certification; while demand for organic apples (and other fruits
and vegetables) continues to grow, supply has been slow to adjust. They wrote that
it is unclear whether the high premium paid at retail for organic fruits and
vegetables is attributable to additional producer costs or to demand. They used a
random coefficients, mixed logit model with a generalized extreme value
distribution of the error term to tease out supply effects from demand effects, and
modeled the retailer as a Stackelberg follower, and upstream producers as a
Stackelberg leader. They showed that the upstream producers’ margin was higher
for organics than for non-organics, and upstream producers capture most of the
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rents for organics, although their share has been decreasing over time. Conversely,
retailers captured most of the rent for non-organic fresh produce.
Timothy Woods, Sayed Saghaian, and Lucia Ona, 2009. “Will Higher Shipping Costs
Drive the U.S. to Source More Localized Produce?” Selected paper prepared for
presentation at the Southern Agricultural Economics Association Annual Meeting,
Atlanta, Georgia, January 31-February 3.
Explored the effects of increased shipping costs on retail prices and discussed a
possible shift in consumption toward local produce. The authors used OLS to
examine the change in consumer prices of three fresh produce commodities with
different values and different degrees of perishability. They showed that, at “peak
diesel prices,” the price of high-value, highly perishable strawberries increased by
2.8 − 5.4%; the prices of lower-value, less-perishable lettuce and low-value, evenless-perishable potatoes increased by 10.8 − 22.1% and 10.8 − 29.0%, respectively.
However, I doubt that the effects of diesel price on retail prices of fresh produce can
be accurately determined using OLS, because of the endogeneity of supply and
demand effects.
Byeong-Il Ahn and Daniel A. Sumner, 2009. “Political Market Power Reflected in
Milk Pricing Regulations.” American Journal of Agricultural Economics, Vol. 91, No. 3,
pp. 723-737.
Developed a model of price differentials allowing, simultaneously, for local
monopolies in fluid milk retail and a Nash equilibrium in the national market for
manufacturing milk products. They simulated the price differentials for fluid and
manufacturing-use milk that would be sought by a monopolist, and specified by U.S.
milk marketing orders, and find that the actual price differentials are only about 7%
of those that maximize monopolist profit. Second, they simulate the policies that
would be set by regional regulators under different welfare weights and find that
the political power of milk producers is also only about 7% of that of a monopolist.
Celine Bonnet, Pierre Dubois, Sofia B. Villas Boas, and Daniel Klapper, 2011.
“Empirical Evidence on the Role of Non Linear Wholesale Pricing and Vertical
Restraints on Cost Pass-Through.” Working paper.
Showed that in the German ground coffee market, the use of retail price
maintenance— in which retail price is specified by the manufacturer—increases the
pass-through rate of price shocks in the supply chain, because retailers have limited
capability of performing strategic price markup.
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Other papers on marketing margins in beef—all cited in Doubhadel, Castillo
and Capps (2009):
Armah. S. 2007. “An Empirical Analysis of Recent Changes in U.S. Beef Marketing
Margins.” Selected paper prepared for presentation at the American Agricultural
Economics Association annual meetings, Portland, Oregon, 29 July - 1 August.
Brester, G. W., and J. M. Marsh. 2001. "The Effects of U.S. Meat Packing and Livestock
Production Technologies on Marketing Margins and Prices." Journal of Agricultural
and Resource Economics 26:445-462.
Hall, L., A. Schmitz, and J. Cothern. 1979."Beef Wholesale-Retail Marketing Margins
and Concentration." Economica 46:295-300.
Lloyd, T. A., McCorriston, S, Morgan, C. Wyn, and Rayner, A. J. 2006. "Food Scares,
Market Power and Price Transmission: The UK BSE Crisis”. European Review of
Agricultural Economics 33(2):119-147.
Marsh, J., and G. Brester. 2004: “Wholesale-Retail Margin Behavior in Pork and
Beef,” Journal of Agricultural and Resource Economics 29:45–64.
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