products within those commodity codes. To evaluate the fitness of customs unit values as the basis for elementary aggregate price indices, we consider two suites of testing protocols. Price dispersion test Our definition of a product is based fundamentally on the price dispersion of all transactions falling within the group defined by the item. We can consider a given domain of export or import transactions defined by a particular set of commodity and transaction characteristics to be a product if there is very little price dispersion within the domain at any given
. Price dispersion test 103. Our definition of an elementary item is fundamentally based on the price dispersion of all transactions falling within the group defined by the item. We can consider a given domain of export or import transactions defined by a particular set of commodity and transaction characteristics to be an elementary item if there is very little price dispersion within the domain at any given point in time. By implication, an elementary aggregate defined by a customs commodity class crossed with destination/source country may satisfy this condition
to adopt for a particular method. Contacts with importing and exporting establishments will be useful to decide on what constitutes outliers or alternative groups. 6.18 However, the use of unit values in such circumstances is born out of limited resources to do otherwise and should not be relied upon. This explains the rationale behind the strategy in Chapter 2 , Section G , of such hybrid indices being part of a staged progression to XMPIs, primarily based on survey data. C.1 Price dispersion test 6.19 Our definition of an elementary item is based