Exercises: Distinguish Surveys, Experiments, and Observational Studies
Work through each section in order. For classification problems, decide
whether a study is a sample survey, an observational study, or a randomized
experiment, and use two separate questions: "Was there random SELECTION?"
(which governs whether results generalize to a population) and "Was there
random ASSIGNMENT?" (which governs whether a difference can be read as
causation). For explanation problems, write in complete sentences.
Fluency Practice
Classify each study and identify the role of randomization.
In the tutoring experiment, students are assigned to attend tutoring or not, and the researchers then record each student's test score. Identify the two variables. The EXPLANATORY variable is ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ . The RESPONSE variable is ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ ̲ .