ICD - Experiments and Observational Studies Lesson

Math_Lesson_TopBanner.png Experiments and Observational Studies

In the last topic, we dealt mostly with samples and sampling techniques. In this section, we will look at experiments and observational studies.

Observational Studies

In observational studies, researchers observe characteristics from samples of an existing population and use the information collected to make inferences about the population. The researcher gathers data without trying to influence responses or impose any controls on the situation.  

There are several key steps involved in designing an observational study.

Observational Study Steps Determine the focus of the study. What is the variable of interest? What information is needed to answer the main question of interest? Develop a plan to collect data. How will subjects be observed? Determine the most appropriate sampling method and select the sample. Collect the data. Describe and interpret the data using appropriate statistical procedures and graphs. Report the findings of the study.

Observational Studies and Experiments

Watch the following videos exploring types of statistical studies.

Video 1 introduces and explores observational studies and experiments.

Video 2 explores more examples of observational studies and experiments.

Statistical Study Example

The following video explores an in-depth example of an appropriate statistical study.

Observational Studies Presentation

It's now time for us to explore and practice working on observational studies.

Experiment

In an experiment, researchers gather data by imposing a treatment and observing responses. A researcher conducts an experiment by assigning subjects to certain conditions and then observing outcomes caused by a variable (the response). These experimental conditions are called treatments.

A simple experiment is used to establish cause and effect, so this type of study is often used to determine the effect of a treatment. In a simple experiment, study participants are randomly assigned to one of two groups. Generally, one group is the control group and receives no treatment, while the other group is the experimental group and receives the treatment.

Basic Principles of Experimental Design Randomization: Experimental units subjects should be randomly assigned to treatment groups. Control: Experimenters need to control any lurking variables, generally by comparing multiple treatment groups. Replication: The experiment should involve many experimental units/subjects.

Experimental Design

The following video introduces and explores experimental design.

Studies, Data Collection, and Qualitative and Quantitative Data

Watch the following videos exploring examples of statistical experiments.

Video 1 discusses and explores types of studies and data collection methods.

Video 2 discusses and explores qualitative and quantitative data, as well as sampling bias, non-response bias, response bias.

Experimental Design Presentation

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