Stamatopoulos, C. Observations on the geometrical properties of accuracy growth
in sampling with finite populations. *FAO Fisheries Technical Paper. *No. 388. Rome, FAO.
1999. 39p.
*Keywords: *Random sampling; Sample size; Sampling
accuracy; Accuracy growth, Accuracy curves; Accuracy boundaries
**ABSTRACT**
A common problem in sample-based surveys that are performed
under operational constraints is how to scale data collection procedures so as
to guarantee an acceptable level of sampling efficiency. This problem
constitutes a frequent concern of fishery administrations with limited budget
and human resources. Generally, lack of any *a priori *guidance on sample
size requirements tends to increase the size and complexity of field operations
and this, in turn, has a direct impact on the logistical aspects of data
collection and data management procedures. The presented study attempts to
provide some answers to the above problem and proposes a supplementary practical
tool for use in the design of sample-based fishery surveys. Its major
assumptions are that the target populations are finite and of known size and
that progressively taken samples are random and independent of each other. Its
main feature is the limited use of probabilistic approaches and the adoption of
geometrical criteria and techniques that would be described as "reasonably
pessimistic". The method is based on a simple definition of a relative index of
proximity of a sample mean to the population mean. This index has several
geometrical properties that are only a function of the population size. Using
these properties it is possible to formulate geometrical constraints that can be
used for predicting a lower limit for accuracy at any sample size between 1 and
the population size. |