Sampling and Observational Studies

This lecture series discusses the studies conducted using surveys. You can use surveys to obtain information about a group of people, but it can be impossible to survey each person if the group is very large. The limited number of people surveyed is called a sample. The way a sample is selected can affect the outcome of a study and its validity. Watch the videos and complete the interactive exercises.

Practice

Types of studies - Questions

1. Angela created and maintains an exercise app where users log their workouts. She wonders if sending users a daily notification that reminds them to use the app will result in them logging more workouts. She releases an update to her app so that half of users will have daily notifications and the other half won't have daily notifications (randomly determined for each user). After a few weeks, she'll see if one group logs more workouts on average than the other group.

What type of study is this, and what is the response variable?

Choose 1 answer:

(A) An observational study where the number of workouts is the response variable

(B) An observational study where notification presence is the response variable

(D) An experiment where notification presence is the response variable

2. According to a study published in the journal Social Psychological and Personality Science, people with religious affiliations live longer, on average, than those without religious affiliations. The study analyzed more than $1,000$ obituaries and accounted for other variables like sex and marital status.

What type of study is this, and what is the explanatory variable?

Choose 1 answer:

(A) An observational study where lifespan is the explanatory variable

(B) An observational study where religious affiliation is the explanatory variable

(D) An experiment where religious affiliation is the explanatory variable

3. A group of researchers wants to know whether graduates from different teacher preparation programs are more likely to stay in the profession. They select a stratified random sample of this year's graduates from several programs. The researchers will contact the graduates after $1, 5,$ and $10$ years to see whether they are teaching in those years.

What type of observational study is this?

Choose 1 answer:

(A) A retrospective study

(B) A prospective study

(D) None of these. It's an experiment, not an observational study.

4. The library where Kara works is planning to add a maker space where members can share equipment and services to create crafts. Kara randomly selected members from their database, then contacted them to ask what kinds of equipment and services they would be most likely to use.

What type of observational study is this?

Choose 1 answer:

(A) A retrospective study

(B) A prospective study

(D) None of these. It's an experiment, not an observational study.