Methodology
The study design was based on two parts
relating to the objectives. To meet the first three
objectives, part one consisted of ‘in-store experiments
and statistical analyses of potato shipment
data from participating retail stores. The second
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component, designed to accomplish objective four,
incorporated a consumer survey of attitudes about
the residue-tested product and consumer satisfaction
with the potatoes. Brief survey forms were
enclosed in one-third of the bags containing residue-
tested potatoes.
In-Store Experimental Design
The store experiment was conducted over a
consecutive seven week period from October 2
through November 18, 1989. In cooperation with
a major New England retail chain, twelve grocery
stores located throughout central and southern
Maine were divided into four groups labeled I to
IV. Each group contained a large, medium and
small sized store assessed in terms of square feet
and customer counts.
Actual sales information on potato sales was
unavailable. As an alternative, potato shipment
data had to serve as a proxy for sales of round
white and residue-tested potatoes. The produce
director at the chain’s headquarters provided three
sets of data for the analysis: 1) shipments of total
round white potatoes received by each store, 2)
shipments of total round white potatoes in five
pound bags, and; 3) shipments of five ~ound
residue-tested round whites. Shipment data were
adjusted for changes in store inventories. During
the first three week pre-test period, shipments of
Maine round white potatoes were monitored to
obtain a basic profile of each store and subsequently,
each study group.
In the four week test period, three of the
four groups sold the round white residue-tested
potatoes in five pound poly bags. These bags
were labeled with the brand logo that identified
the potatoes as tested for pesticide residues and
were displayed beneath a price card containing the
same logo. As the basis for comparison, the test
stores also sold the standard Maine round white
potatoes in five pound bags. Produce ma~agers
were asked to sell the two types of potatoes in
close proximity and in displays of equal size.
The residue-tested potatoes were virtually
identical to the standard round whites in terms of
the physical appearance of the potatoes. Weekly
store visits were conducted to ensure that the