Understanding Randomized Experiments and Observational Studies

Front

Distinguish between a randomized experiment and an observational study

Back

A randomized experiment involves randomly assigning subjects to different groups to test a specific variable, while an observational study involves observing subjects without manipulation.

Front

Understand the advantages of randomized experiments

Back

Randomized experiments help eliminate bias, establish causation, and provide more reliable results by controlling for confounding variables.

Front

Understand how confounding can affect the results of an observational study

Back

Confounding occurs when an outside factor affects the results, making it difficult to determine the true relationship between variables in an observational study.

Front

Describe various types of observational studies

Back

Observational studies include cohort studies, case-control studies, and cross-sectional studies, each with different methods of data collection and analysis.

Front

Experimental units

Back

Individuals who are studied in an experiment, which can be people, animals, plants, or things. When they are people, they are sometimes called subjects.

Front

Outcome or response

Back

What is measured on each experimental unit.

Front

Treatments

Back

The procedures applied to each experimental unit.

Front

Diagram showing the relationship between Experimental Units (Subjects), Treatments, and Outcome or Response.

Back

Illustrates the flow from experimental units to treatments and then to outcomes or responses.

Front

Experimental Units, Treatments, Outcomes

Back

Scientists conduct a study to determine which of three types of seed results in the largest wheat yield.

Front

Steps in the Seed Experiment

Back

1. Prepare three identically sized plots of land with similar soil types. 2. Plant each type of seed on a different plot, choosing the plots at random. 3. Water and fertilize the plots in the same way. 4. Harvest the wheat and measure the amount grown on each plot. 5. Compare the yields to determine the best seed type.