Question

Match the study with the type of study design. A type of study design can be used more than once.

a. Cross-sectional study

b. Randomized controlled trial

c. Prospective cohort study

d. Ecological study

e. Retrospective cohort study

1.All UMD students are surveyed on the first day of class, asking about their current vaping use.

2. A group of adolescents are randomized to receive either a comprehensive sex education program or an abstinence-only program. Pregnancy rates are compared at at 3 years post-program.

3. A group of Baltimore City residents who were exposed to lead paint as children are followed over time and surveyed at regular time points about their incidence of cancer.

4. A telephone survey of P.G. County residents asking about their neighborhood access to healthy food.

Answer 1

A cross sectional study is an observational study in which data regarding each subject is recorded at one point in time.  

A cohort study is a longitudinal observational study, which means that the individuals are observed for a time period and observations are noted. However, no intervention is done during this study.

• In a prospective cohort study, the group does not have the outcome, but have a risk factor ( exposure). Here they are followed up for a certain time period to look for the outcome.
• In a retrospective cohort study, the group already has the outcome. Here, we go back to the past history and past medical records to see if they had exposure previously.

Ecological study is an observational study for an entire population rather than at an individual level.

Randomized controlled trial: (RCT) A study in which people are allocated at random into study and control groups. The study group receives a paticular intervention whereas the control group doesnot . It is an example of an interventional study.

------------------------------------------------------------------------------------------------------------------------------

Now, let us look at each of the questions  :

1.All UMD students are surveyed on the first day of class, asking about their current vaping use.

Here, all the students are surveyed on a particular day. There is no intervention. No follow up. Just, the observations are noted. So it is a Cross-sectional study.

2. A group of adolescents are randomized to receive either a comprehensive sex education program or an abstinence-only program. Pregnancy rates are compared at at 3 years post-program.

Here, two groups are formed -the study group receiving the sex education program and control group who does not receive this. This is an example of Randomised controlled trial.

3. A group of Baltimore City residents who were exposed to lead paint as children are followed over time and surveyed at regular time points about their incidence of cancer.

Here, those who were exposed were followed up for a certain time. The outcome is some of them develops cancer whereas some donot. So, this is a Prospective cohort study.

4. A telephone survey of P.G. County residents asking about their neighborhood access to healthy food.

Here, the residents access to healthy food is studied, i.e, we are studying the food security of the entire population. This is an example of an Ecological study