STATA 11 for Windows SAMPLE SESSION - Food Security Group ...

Stata 11 Sample Session Section 2 – Restructuring Data Files – Table Lookup & Aggregation
• c-q1a.dta: This file contains data on household
roster characteristics. It is at the householdmember
level. We need to use the variables ca3
(age) and ca4 (sex) in this exercise to compute
the number of adult equivalents per household.
• c-q4.dta: This file contains data on crops
produced by the household. The variables we
need to calculate the total production of the
household are:
a. prod - contains the codes for the
agricultural crop produced.
b. p1a - contains the codes for the unit in
which the production was measured (100 kg
sack, 50 kg sack, etc).
c. p1b - contains the number of units produced
for the year.
Note that the unit of production is not a standard unit for
each crop. For example, a "100 kg sack", as the term is
used in Mozambique, weighs 100 kg only when the sack
is filled with maize. When it is filled with manioc root, it
weighs much less than 100 kg. Thus, we need conversion
factors to be able to convert each of the units in which
production was actually measured to our standard unit,
which is the kilogram.
• conver.dta: This is a table-lookup file. This file
was created specifically to handle the problem of
converting non-standard units to a standard unit.
For each product-unit combination there is a
conversion factor to convert the measurement to
equal the weight in kilograms. In other words,
there is a different conversion factor for each
product-unit combination. For example, the
conversion factor for a 50 kg sack of rough rice is
39.44; for a 50 kg sack of cotton it is 17.5, while a
50 kg sack of peanuts is 41.67. The variables in
this file are:
a. prod - product (crop) code
b. unit - unit of measure
c. conver - conversion factor (equal to the
number of actual kilograms for the
combination of prod and unit)
Below, a sample of data from CONVER.DTA shows that:
rice (prod=7) measured in a 20 liter can (unit=8) weighs 19 kg;
rice (prod=7) measured in a 50 kg bag (unit=24) weighs 53 kg;
beans (prod=30) measured in a 20 liter can weighs 17 kg;
beans (prod=30) measured in a 50 kg bag weighs 47 kg.
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