Stat 095 What is Tidy Data?

• Tidy data has rows that are called cases or observations.

• Tidy data has columns that are variables or attributes.

• Variables can be quantitative or categorical

Tidy data is narrow:

##   Student Year GPA
## 1   Emily    1 3.2
## 2   Emily    2 2.7
## 3   Emily    3 3.4
## 4   Emily    4 3.8
## 5    Zack    1 2.8
## 6    Zack    2 3.1
## 7    Zack    3 3.2
## 8 Jasmine    1 3.5
## 9 Jasmine    2 3.1

• whereas Un-Tidy data is wide:

##   Student GPA1 GPA2 GPA3 GPA4
## 1   Emily  3.2  2.7  3.4  3.8
## 2    Zack  2.8  3.1  3.2   NA
## 3 Jasmine  3.5  3.1   NA   NA

To see what each variable represents in a data set, we look at a codebook:

• Here is the codebook for the Names of children, as recorded by the Social Security Administration:

help(BabyNames)

Association Rules

• This a method used to predict customer behavior

• We’ll start by working by hand, then with Excel, then with R …