Abstract:
The purpose of the present study has been the specification
and measurement of the characteristics of the intraseasonal demand
for fresh Bartlett pears. In particular, the study has focused
attention on a particular producing area, the Rogue River Valley
of Oregon.
The intraseasonal analysis for fresh Bartlett pears was
performed using two alternative specifications on the model of
the Bartlett pear market. In the first model, it was assumed
that each bi-weekly supply function was perfectly inelastic and
that the supply quantity was determined by factors other than the
current price of fresh Bartlett pears. The bi-weekly demand
functions were estimated by the ordinary least-squares method.
In the second model, it was assumed that growers set prices on
the basis of the market prices they had most recently observed
and of their total holdings of Bartlett pears. A price predicting
equation was then estimated by ordinary least-squares and the
resulting predicted prices were used in estimating the parameters
of the demand functions.
In both models, the analysis was performed alternatively
by subperiods and by marketing seasons. The latter differed from
the former in that the years under study were separated into sets
of years having the same number of subperiods.
The subperiod analyses were performed by two approaches:
1) a demand equation was estimated for each subperiod, and 2) a
single equation was specified in which the observations were indexed
by year and by subperiod. Dummy variables and product
terms of the quantity variables were employed to permit shifts
in the level and the slope of the demand function. The marketing season
analyses were performed by the second approach.
The results obtained from the investigation of the two
hypotheses show that the Medford demand function changes level
within season. This finding is more pronounced in the marketing season
analysis. The marketing-season analysis of the first model
indicated that changes in the slope of the demand function also took
place. These results suggest that there is, in fact, a seasonal
pattern to the derived demand facing the sellers of fresh Bartlett
pears from Medford district. The elasticity of the Medford
demand curve changes in response to the shifts of the California
supply curve and possibly the appearance of the winter varieties.
The two hypotheses yielded consistent results.
