Exam 12: Causality

Design an observational study on a topic of your choice. Make sure that there are at least 2 independent variables in the study. Alternatively, you may use a study you designed for the essay questions in prior chapters, if appropriate. Discuss what steps you would take to assess the internal validity of a causal relationship between the outcome and one of the independent variables. Explain the reasoning for your assessment process.

What is "postmeasurement" in the context of an experimental study? Explain with an example.

What does 'placebo effect' mean in the context of experimental studies?

How could a longitudinal observational study ensure 'time order'?

Why is there a control group in clinical trials?

Provide an example of an experimental study. Identify the treatment and control groups of the study.

What is a quasi-experiment? Explain this type of research design with an example.

A study found that drivers who resided in Trenton, New Jersey, were more prone to car accidents than other drivers in the state. The study did not look at several other characteristics of the driver, such as destination, location of the accident, and, age of driver, among others. What is this type of conclusion made by the study called, and why? Explain your answer.

Distinguish between random assignment and random sampling. Illustrate with an example.

Consistency of association refers to an association between two variables that has been observed in several different samples, and, in different study designs.

Why does an observational study have a greater risk of selection bias than an experimental study?

How is an observational study different from an experimental study? Illustrate with an example.

If an association between two variables is determined to be causal, which two criteria could be used to strengthen the validity of that determination?

Design an experimental study on a topic of your choice, with at least two independent variables. Explain the process you would use to assess the internal validity of a causal relationship between the outcome and one of the independent variables. How does this process compare, in terms of complexity, with the process you used in question 1?

A causal relationship is one where a change in the response variable causes a corresponding change in a predictor variable, keeping all other variables constant.

In a study, it was found that a 1-unit change in a variable X caused a 3.2 unit change in variable Y. What is this phenomenon termed as?

A sample survey of voting trends in Florida's mid-term election results would have high external validity but may have low internal validity.

Once causality is established by assessing the three primary criteria for presence of the phenomenon, which two additional criteria help in strengthening the case for causality? Explain the process for applying these two criteria.

What type of a study is a 'Natural Experiment'?

Discuss the importance of ensuring internal validity in research studies. What are the implications if internal validity of a causal relationship cannot be confirmed in a research study?