Chap 1.4: Types of Data and Some Simple Graphical Displays

Univariate data set

Consists of observations on a single variable made on individuals in a sample or population. It focuses on analyzing one characteristic without considering other variables.

Types of univariate data sets

Categorical and numerical.

Variable

A characteristic whose value may change from one observation to another.

Data

A collection of observations on one or more variables.

Categorical data set

It is qualitative if the individual observations are catergorial responses.

Numerical data set

It is quantitative if each observation is a number.

Types of numerical data

Discrete and continuous

DIscrete numerical variable

A numerical variable results in discrete data if the possible values of the variable correspond to isolated points on the number line.
(It can only have specific values)

Continuous numerical variable

A numerical variable results in continuous data if the set of possible values forms an entire interval on the number line.
(It can take on any value in an interval)

Possible values for the variable number of text messages sent are 0, 1, 2, 3,…, which means

these are isolated points on the numebr line, so this data set consists of discrete numerical data.

Examples of continuous data

The number can be measured, so it can be decimal, whole, fraction, etc.
- Temperature

Example of discrete data

It can be counted (natural and whole number)
- Rolling 6 sided dice