STAT 301 Lab

Lab 3: Type of Variables

T.A.: Yixuan Qiu

Reminder

• Contribute your data in the front
• Pick up handout and your previous lab sheet
• Open Blackboard and download SPSS instructions
• Slides at http://statr.me/courses.html
• Don't need to do #8
• You need to print off graphs for this lab

Types of Variables

• Quantitative variable
  • Takes numerical values
  • Can have arithmetic operations, such as adding and averaging
  • Example: age, height, temperature, etc.
• Categorical variable
  • Places an individual into one of several groups or categories
  • Example: colour, major, etc.

Graphing Tools

• Quantitative variable
  • Histogram, Stemplot, etc.
• Categorical variable
  • Bar Graph, Pie Graph, etc.

Entering Data

• Change variable type to string for categorical variable
• Two ways to enter categorical data
  • Enter value sequentially as it is (Left)
  • Enter summarized values and their counts (Right)

Entering Data

• For the second approach, remember to WEIGHT CASES
• Read instructions carefully

Distribution Shapes

• Skewness
  • Skewed left: Long Tail on the left
  • Skewed right: Long Tail on the right
• Modes
  • Unimodal: One major peak
  • Multimodal: More than one peaks