Question

Describe two methods that a researcher can use to avoid obtaining a non-representative sample

Answer 1

One method involves taking our population and assigning every person in this population a certain number on a piece of paper. After this has been done, randomly pulling out numbers of people from the population to get a randomized sample can be done. 

Another method is stratified sampling where you proportionally divide the sample into smaller and smaller subgroups so that they are always evenly matched and representative for their subgroup - in this way you avoid having a non-representative sample.