In this paper we try to discuss the precision in of some
probability samplings with emphasis on systematic
sampling. Precision is a measure of how close an estimator
is expected to be to the true value of a parameter, which is
usually expressed in terms of imprecision and related to the
standard error of the estimator. Less precision is reflected
by a larger standard error.( Valerie J. Easto & John ,1997).
Sampling error and bias relate to precision and accuracy. A
measurement is precise if it obtains similar results with
repeated measurement (or repeated surveys).A
measurement is accurate if it is close to the truth with
repeated measurement (or repeated surveys). Because bias
in survey, may lead to make inappropriate decisions about
programmes based on invalid results, and lead to fail to
provide needed services or waste resources on providing
unneeded services. Bias may lead to grossly wrong
conclusions, while having not quite enough precision may
only decrease confidence in the survey results.