which one is non viable export sampling method -
1. settle plate method 2. air sampler
3. air exposer method
4. auto trap sampler method
Answers
Explanation:
A. Introduction
6.1 Price surveys normally collect information on products—their prices and price-
determining characteristics—from establishments. For foreign trade in goods, however,
administrative sources (customs records) usually are available from which compilers can
calculate unit values. The central question of external trade price indices thus arises: is a unit
value a price and a valid data element for constructing an export or import price index? Can
we, therefore, use it rather than spending the effort and cost to collect prices from
establishments? In Chapter 2 concerns were expressed about the widespread use of unit
values as surrogated for price indices, even at the most detailed level of Harmonized System
classes of goods, and even if subdivided by source (import) or destination (export) country. A
strategy was outlined in Chapter 2 for countries whose trade price indices rely on unit values
for moving from such a system to a hybrid system, that includes actual prices surveyed from
establishments, and subsequently, resources permitting, to one in which most of the
commodities included has prices based on survey information. A price must be associated
with a given and complete description of the product encompassing the product and
transaction characteristics that affect the exchange value or price. Unit values more often
than not are averages across a variety of such descriptions, and thus, they are subject to
composition effects. Unit values will change not only because of change in the price of any
given product description within the HS class, but also because an HS class contains a
different assortment of priced product descriptions from month to month, quarter to quarter,
and year to year.
6.2 More often than not, as outlined in Chapter 2, a given HS class, even crossed with
country of origin (import) or destination (export), does not define a homogeneous class of
transactions. As a product description, it is insufficient. Unit value indices are used by many
countries and a move to price indices has resource consequences. The preferable, though
resource-intensive, approach is a one-off switch to an index based on establishment-based
price surveys. This may be prompted by a country joining a customs/monetary union. While
the main problem with simply introducing a new program is the resource cost, if a PPI
program is already established, there will be natural synergies between the export and import
price indices and the PPI. If resource constraints preclude this, one possibility is to identify
whether there are particular products less prone to unit value bias and utilize unit value
indices only for these sub aggregates in a hybrid overall index. The compilation techniques
for such hybrid indices was outlined in Chapter 2, Sections E.1 and E.2 and an example is
provided in table 6.2 of this Chapter. The use of hybrid indices is a strategic option outlined
in Chapter 2 Section E. It is stressed that this is a strategy for statistical offices with limited
resources. The intention of this gradualist approach is that it be a staged progression for an
eventual move to a system in which the primary data source would be survey based prices of
well specified representative items. A gradualist approach has major resource benefits. There
will be some “low-hanging fruit,” establishments responsible for relatively high proportions