# Chapter 1 - Introduction to Data

### Learning Objectives

- Identify the type of variables (e.g. numerical or categorical; discrete or continuous; ordered or not ordered).
- Identify the relationship between multiple variables (i.e. independent vs. dependent).
- Define variables that are not associated as independent.
- Be able to describe and identify the difference between observational and experimental studies.
- Distinguish between simple random, stratified, and cluster sampling, and recognize the benefits and drawbacks of choosing one sampling scheme over another.
- Identify the four principles of experimental design and recognize their purposes: control any possible con- founders, randomize into treatment and control groups, replicate by using a sufficiently large sample or repeating the experiment, and block any variables that might influence the response.

### Supplemental Readings

### Videos

*OpenIntro* provides a number of videos. You may find these helpful while reading the chapter.

Case Study: Using Stents to Prevent Strokes

Data Basics: Observations, Variable, and Data Matrices

Observational Studies and Sampling Strategies

Using Randomization to Analyze a Gender Discrimination Study