Chapter 3: Population and Sampling Procedures from quantitative studies

In quantitative studies, it is particularly important to understand who your population and who it is not. Therefore, the first thing to address in this section is who is your target population. Again, the best way to think about this is who does the study generalize to? So if you were testing undergraduates, that is who your population really is (contrary to many of the old studies who make the case that they are similar to the population in general). Next, you want to state appropriately how large the population is that you are using. This may take some detective work to get at.

The next section is Sampling. You rarely can test the entire population; instead, you must strategically sample to make sure you get a representative group. How will you do that? There are many ways that have been suggested, the important thing is to realize the cost and benefit of each method and how they affect your study. Let's say that you decide that you will post flyers and have people contact you if they want to participate. There are a number of costs of doing it this way: you will only get people who frequent where you are posting flyers, you will only have people who volunteer, and only people who have a phone to contact you. None of these issues are fatal flaws, but you need to be aware of them.

What are your inclusion criteria (who can participate) and exclusion criteria (who cannot participate)? Think details. If you are doing an internet survey on survey monkey- inclusion criteria include: people who can read English, have access to a computer, as well as any issues related to your population (e.g., divorced for a year).

You will need to do a power analysis to determine how large your sample should be. Check with your methodologist, as to whether they have a preference as to how to do it. I generalize recommend using one of the power analysis calculators available online (do a search for power analysis calculator). You need to give the website that you used for the calculation and why you used the parameters that you entered. You may need to talk to your methodologist about this aspect. 

Next time we will continue with quantitative studies and look at Chapter 3: Recruitment. Do you have an issue or a question that you would like me to discuss in a future post? Would you like to be a guest writer? Send me your ideas! leann.stadtlander@waldenu.edu