Explain how generalizability is evaluated. What are the two types of generalizability mentioned in the text? How do they differ and how are they similar?

Question

What will be an ideal response?

Answer 1

After clearly defining the population we will sample, we need to determine the scope of the generalizations we will seek to make from our sample. Let us say we are interested in the extent to which high school youth are fearful of being attacked or harmed at school or going to and from their schools. It would be easy to go down to the local high school and hand out a survey asking students to report their level of fear in these situations. But what if my local high school were located in a remote and rural area of Alaska? Would this sample reflect levels of fear perceived by suburban youth in California or urban youth in New York City? Obviously not. Often, regardless of the sample utilized, researchers will assert that “this percentage of high school students are fearful” or “freshman students are more fearful than seniors,” as if their study results represented all high school students. Many researchers (and most everyone else, for that matter) are eager to draw conclusions about all individuals they are interested in, not just their samples. Generalizations make their work (and opinions) sound more important. If every high school student were like every other one, generalizations based on observations of one high school student would be valid. This, however, is not the case.
Generalizability has two aspects. Can the findings from a sample of the population be generalized to the population from which the sample was selected? Sample generalizability refers to the ability to generalize from a sample (subset) of a larger population to that population itself (e.g., using those Alaskan students’ survey results to speak more generally about rural students’ perceptions of fear). This is the most common meaning of generalizability. Can the findings from a study of one population be generalized to another, somewhat different population? This is Cross-population generalizability and refers to the ability to generalize from findings about one group, population, or setting to other groups, populations, or settings. We use the term external validity to refer only to cross-population generalizability, not to sample generalizability.