What is statistics? Only one of the most awesome types of math EVER! Statistics helps us make sense of the world around us by providing methods to describe and analyze **data**. Data comes in many forms:

Type of data | Description | Examples |

Discrete | Data for which there are only whole number values | Number of people, Number of countries you’ve visited, price in cents |

Continuous | Data for which any value in-between whole numbers is possible | Height, distance, length of time |

Nominal | Data listing names of something | Type of relative (mom, aunt, uncle, cousin, grandfather), type of car |

Ordinal | Data that describes the rank/order | Year in school (1st grade, 2nd grade), choice on rating scale (e.g., 1-5), months |

Interval | Numerical, ordinal data with evenly-spaced intervals | Degrees in Fahrenheit |

Ratio | Interval data where 0 has a clear meaning | Time |

This book focuses on describing and analyzing continuous data, but in Lesson 16 we get into categorical data.

The examples of each type of data above are **variables**. The actual data values collected for each variable *vary*; for example, if we recorded the temperature every evening at 8:00 pm (where the variable is “degrees in Fahrenheit”), we would record many different values.

Always analyze data with a critical eye. You should know how a survey or experiment was conducted, who is in the sample, and how the variables are measured. This textbook will help you develop a sense for numbers so that you can tell if something fishy is going on.

For one thing, it’s crucial that you always know exactly how variables are measured. If the variable is height, are you measuring in inches? Centimeters? It’s relatively easy to determine a unit of measurement for height, but what about the variable happiness? Happiness, love, ambition, etc. are examples of **constructs**, variables that can’t be easily defined or measured.

For constructs, we have to determine an **operational definition**; in other words, a precise way of measuring them. For example, maybe we could measure happiness by the number of times people smile or laugh each day.

For constructs, we have to determine an **operational definition**; in other words, a precise way of measuring them. For example, maybe we could measure happiness by the number of times people smile or laugh each day.

Throughout this book, you’ll use operational definitions to analyze variables and the relationships between them. You’ll also learn how to draw conclusions about an entire **population** (e.g., all residents of the United States) based on actual population data or a **sample** of that population (e.g., 5000 randomly selected residents of the United States). Samples must be representative of a population in order to draw inferences about the population; for this to happen, the sample should be chosen randomly, meaning that each member of the population has an equal chance of being chosen to be in the sample.

**This is a preview of Lesson 1. To access the full book, please purchase a hard copy or a digital version. If you opt for the digital version, you will receive a link via email within 1 business day.**

Continue to Lesson 2, or select a lesson below.

Street-Smart Stats homepage

Lesson 1: Introduction to Statistical Research Methods

Lesson 2: Visualizing Data

Lesson 3: Central Tendency

Lesson 4: Variability

Lesson 5: Standardizing

Lesson 6: Normal Distribution

Lesson 7: Sampling Distributions

Lesson 8: Estimation

Lesson 9: Hypothesis Testing

Lesson 10: t-Tests for Dependent Samples

Lesson 11: t-Tests for Independent Samples

Lesson 12: Intro to One-Way ANOVA

Lesson 13: One-Way ANOVA: Test significance of differences

Lesson 14: Correlation

Lesson 15: Linear Regression

Lesson 16: Chi-Squared Tests

Afterward

Index

How do you enter data from a google docs spreadsheet into R?

Hi Rick! Just download the Google spreadsheet as a csv and then save it to your working directory. When you input it into R (method 2 above), just make sure you use the same file name. Lesson 2 page 1 has an R tutorial that uses data from a Google spreadsheet and walks you through inputting it into R.