when it comes to data, size isn’t everything. Opinion polls such as Gallup’s are based on samples of the voting population. This means opinion pollsters need to deal with two issues: sample error and sample bias. Sample error reflects the risk that, purely by chance, a randomly chosen sample of opinions does not reflect the true views of the population. The ‘margin of error’ reported in opinion polls reflects this risk, and the larger the sample, the smaller the margin of error.
