A note on the correspondence between horizontal and vertical price transmission.

Horizontal (vertical) elasticities of price transmission in a competitive market can be positive or negative in sign depending on whether observed changes in market prices are triggered by shifts in the supply or demand for the commodity or by changes in trade (marketing) costs. These facts suggest estimates of horizontal (vertical) elasticities of price transmission obtained from empirical models that exclude trade (marketing) costs will suffer from attenuation bias. The attenuation bias is apt to cause inferences about market efficiency to be more pessimistic than is warranted. [ABSTRACT FROM AUTHOR]