Statistics 216 Notes

*sanely* ordered. We’ll see how long this lasts.

Coin flipping activity

maybe check out Benford’s Law if you’re interested in learning more.

The lecture covered part of section 1.1 in the book:

What is statistics? The study of data.

What is data? Data is tables.

What are tables? Tables are rows and columns.

What are rows? Rows are units, the subjects of inquiry.

What are columns? Columns are variables, the characteristics of the units.

In class we came up with two little examples for data:

student | over 21 | hair color | male/female |
---|---|---|---|

Bob | no | brown | male |

Sarah | no | black | female |

Jean | yes | brown | female |

student | new worth | height | distance home |
---|---|---|---|

Kristin | $2,000 | 5’5” | 200 mi |

Jordan | $1,000,000 | 6’0” | 15 mi |

Brad | $12 | 5’7” | 2,012 mi |

Note the difference in the types of variables in the table on the left from the types of variables in the table on the right. The variables in the table in the right can be numbers. We can add them or multiply them or divide or whatever. They are called **quantitative variables**. The variables in the table on the left aren’t really numbers. We can’t add them up or multiply them. We call these types of variables **categorical variables**. One important point: note that the “over 21” variable is categorical. Some folks mistakenly consider this a quantitative variable because it *involves* a number. It is, in fact, a categorical variable.

We talked a little about how we could expect some of the variables to be distributed. I said that I figured that a height variable would look something like this:

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