Any sample collected is done to obtain information representative of the population. And as such there will be uncertainty on the measurements taken due to not being able to test the entire population.
Uncertainty around any type of estimate should always be quoted to emphasize the level of statistical confidence in the results, to show whether the estimate can be relied on when making an evidence-based decision, and quite simply, to show the range of values the estimate of the population could fall within.
As mentioned in Chapter 4, quoting uncertainty as “95% of ...
