Sampling error and selection bias (cont.)

Avoiding sampling error

Sampling error can be reduced by increasing sample size. This is reflected in confidence intervals, with larger sample sizes resulting in narrower confidence intervals.

Source: Chris Wild, https://www.stat.auckland.ac.nz/~wild/WPRH/

However, larger sample sizes means greater costs, both financial and in terms of time. Therefore a balance must be found between reducing sampling error through increased sample size, and keeping costs to an acceptable level.