Price transmission in the cocoa chocolate chain
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Price Transmission in the Cocoa-Chocolate Chain. Catherine Araujo Bonjean CNRS , CERDI Jean-François Brun Université d'Auvergne, CERDI First Conference on Economics and Politics of Chocolate Leuven 16-19 September 2012. Introduction.

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Price Transmission in the Cocoa-Chocolate Chain

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Price Transmission in the Cocoa-Chocolate Chain

Catherine Araujo Bonjean


Jean-François Brun

Université d'Auvergne, CERDI

First Conference on Economics and Politics of Chocolate

Leuven 16-19 September 2012




We explore the channels of transmission of the fluctuations inthe world price of cocoa beans to the consumers of chocolate bars in France.

Special case of a more general pattern of asymmetric vertical price transmission in the commodity-end product chain(for instance from crude oil to gasoline retail price)

Consumers often have the feeling that retail prices respond faster to an increase in the price of raw material than to a decrease.

1. Introduction

1. Introduction

Cocoa beans and chocolate bar prices 1955 – 2011

constant euros (100 = 1990)

The cocoa price fluctuations are transmitted to consumers with a delay of about one year.

Pass-through of cocoa fluctuations to chocolate bar price seems to be asymmetric. Sharp increases in the cocoa price are more readily transmitted to consumers than price falls.

Two types of asymmetry with different origins

First, asymmetry in the transmission of positive and negative shocks may be due to imperfect competition in the processing/distribution chain.

The chocolate processing and manufacturing sector is highly concentrated since the second half of the 80s.

At the world level six companies control more than 90 % of cocoa processing, manufacturing and distribution.

In France, the chocolate industry is dominated by 3 companies (Barry Callebaut, Cargill, Cémoi)

In a recent paper we showed that the Cote d’Ivoire loose its market power to the benefit of the chocolate industry

1. Introduction

Menu costs

Second, asymmetry in transmission of large and small shocks due to “menu costs”

Changing price is costly. Adjustment costs in the packaging and distribution stage of the marketing process are a possible cause of asymmetry in price transmission according to the size of the shocks

processors and/or distributors respond to “small” input price fluctuations by increasing or reducing their margins. The output price adjust only if the fluctuations in the input price exceed a critical level

1. Introduction


Non-competitive markets and adjustment costs may thus result in nonlinear price dynamic. Two hypotheses are tested:

the chocolate price only adjust to large shocks in the cocoa price

cocoa price increases are more rapidly and fully transmitted to consumers than decreases.

1. Introduction

Model of price transmission

In the standard cointegration framework:

The long run relationship between the two prices is given by:


Pc: chocolate price; Pb: beans price

The short run dynamic is given by the error-correction model (ECM):


 is the speed of adjustment of Pt to a deviation of Pt from its long-run equilibrium.  is constant

2. Econometric model

Non linearcointegation model

ECM with 3 regimes


1 and 2: two thresholds.

The speed of adjustment differs according to the size of the past disequilibrium (t-d).

Regime switching occurs, with a delay d, when the error term goes above or below the threshold

Hypotheses: m = 0 and  l <  u < 0

2. Econometric model


A two-step approach based on Engle and Granger methodology

First step: estimate the long run equilibrium relationship between the price of chocolate and the price of cocoa and apply cointegrationtests to the equilibrium error.

Second step: test for nonlinear threshold behaviour and identify the best fit model, then estimate the short run model of price adjustment.

2 samples: monthly data on the period January 1960 to February 2003 (518 observations); annual data available on a longer period of time, 1949 – 2011

2. Econometric model

Estimation results. Monthly data: 1960.01 – 2003.02

3. Main results

FMOLS estimate of the cointegratingequation

p-value are in parentheses

Exogeneity test from VECM

Cointegration tests results

3. Main results

The standard Engel-Granger test (no cointvs linear coint) does not reject the hypothesis of cointegration but the Enders-Siklos test (no cointvsnonlinear coint) rejects the null of no cointegrationwhenusing the consistent estimate of the threshold

Testing nonlinearity

1. Tsay (1989) non parametric test

2. Hansen sup-F test based on nested hypothesis tests. Test the null of a TAR(i) model, against the alternative of TAR(j) model:

Siis the sum of squared residuals under the null of i regimes.

Sjis the sum of squared residuals under the alternative hypothesis of a j-regime TAR(j)

We use Hansen (1996) bootstrap procedure to approximate the asymptotic distribution of F correcting for heteroskedascity

3. Main results

Testing nonlinearity

3. Main results

TAR(3). Dependant variable: t

the linear model isrejected to the benefit of a TAR(3) model for the errorterm

tis not stationnarywithin the band but stationnary in the outerregimes


Pc adjustsfaster to large negativedeviationsthan to large positive ones

Robustness tests: annual sample

The analysis is duplicated on a sample of annual prices covering the period 1949 – 2011. Two specifications of the long run relationship between the chocolate and the cocoa prices are considered.

The first one is a linear model with two variables corresponding to specification tested on monthly prices

The second one is a log linear model including an additional variable: the consumer price index in France

4. Robustness

Robustness tests: annual sample

The no cointegration hypothesis is rejected and the non linearity tests reject the linear model of adjustment against a TAR(3) model :

Cointegrationis inactive as long as discrepancies from long term equilibrium lie within the band; the process is mean reverting in the outer regimes.

The coefficients size suggests that large disequilibria resulting from an increase in the price of cocoa are corrected more rapidly than large discrepancies resulting from a decrease in the price of cocoa

4. Robustness

Timing of regime switching

5. Conclusion

Monthly data

Annual data


Most of the time, the price of chocolate did not adjust to changes in the price of cocoa beans.

The chocolate price adjusts only to large disequilibrium. This is may reflect the presence of adjustment costs.

The chocolate price corrects quickly disequilibrium following historical booms in the cocoa market but reverts back more slowly when cocoa price decline. This is consistent with a non-competitive market structure.

Thank you for your attention

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