To determine which of the variables in the given data set is a categorical variable, let's first understand the nature of each variable:
1. Hole Number: This represents the numerical label assigned to each hole. It is a numerical variable.
2. Yards: This indicates the length of each hole in yards. It is measured in numerical units and represents a numerical variable.
3. Bunkers: This shows the number of bunkers (sand traps) present on each hole. Since this is counted and measurable, it is also a numerical variable.
4. Difficulty Level: This describes the perceived difficulty of each hole and is expressed in qualitative terms like "easy," "moderate," and "hard." This type of data represents categories and is, therefore, a categorical variable.
Based on these descriptions, the categorical variable in the data set is the difficulty level.