Stigler observed that search (except for infrequent one-off purchases) was a dynamic process and that search in one period depended to an extent on previous results. Which factors do not have a significant effect on the relative levels of successive search efforts?

a) The correlation of the relative prices offered by sellers over time.

b) The size of the purchase relative to buyer income

c) The time interval between purchases

d) The degree of goodwill felt toward a seller which reduces the incentive to "shop"

e) All of the above have an effect