STAT Chapter 2 Jot Notes
Types of Data and Information
- the objective of statistics is to extract information from data
- variable: some characteristic of a population or sample (represented by X, Y, Z)
- values: the possible observations of the variable
- data: the observed values of a variable
3 Types of Data
- Interval/quantitative/numerical: real numbers (ex. height, weight, income, distance)
- Nominal/qualitative/categorical: values are in categories (ex. single =1, married = 2, divorced = 3)
- Ordinal: appears to be nominal, but the order of their values have meaning (ex. poor = 1, fair = 2,
good = 3, excellent = 4) The magnitude of the values are not important, but the order is
- The difference between interval and ordinal data is that for interval data, the differences
between values are consistent and meaningful (ex. 85-80 has the same 5 value difference as 75-
70. However, 6-18-22-56-78 coding of ordinal data is not consistent, ordinal data only tell order,
not value between data)
Calculations for Types of Data
- Interval Data
All calculations are permitted (often the average is calculated)
- Nominal Data
Does not calculate average
Instead compute the % of occurrence of each category
- Ordinal Data
Most important aspect of ordinal data is the order of the values
Median is the most important
Hierarchy of Data

More
Less