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An important consideration when sampling from a population is that of random error, which results from chance variation in the members of any sample taken from a larger population. Random error may affect the conclusions you draw from a study by affecting the precision of a descriptive study, or the power of an analytic study.

An important consideration when sampling from a population is that of random error, which results from chance variation in the members of any sample taken from a larger population. Random error may affect the conclusions you draw from a study by affecting the precision of a descriptive study, or the power of an analytic study. However, although the magnitude of random error can be quantified to some degree, its direction cannot be predicted due to its random nature.

==Precision==  

==Precision==  

The '''precision''' of an estimate is a measure of the 'repeatability' of this estimate if the same study was conducted again. Therefore, it is a measure of the random error inherent in a sample, which in the case of descriptive studies is closely associated with the '''confidence interval'''.  

The '''precision''' of an estimate is a measure of the 'repeatability' of this estimate. Therefore, it is a measure of the random error inherent in a sample, which in the case of descriptive studies is closely associated with the '''confidence interval'''.  

==Confidence intervals==

==Confidence intervals==