Chapter 1Lesson 1.4

The Role of Statistics and the Data Analysis Process

1.4: Types of Data and Some Simple Graphical Displays

Vocabulary

• Univariate Data Set:A data set consisting of observations on a single characteristic/variable.

• Bivariate Data Set:A data set consisting of observations on two characteristics/

variable.

Examples?

VocabularyVariable:Any characteristic whose value may change from one individual/object to another.

• Categorical e.g. hair color

• Quantitative (Numerical)e.g. how many hours of fun

Example: See Handout

Vocabulary

• Categorical

• Quantitative– Discrete variables can take one of a finite number of

distinct outcomes (isolated points on a #-line.)• Example:

– Continuous variables can take any numeric value within a range of values (interval on a #-line.)

• Example:

Frequency and Relative Frequency

• Refer to pg.13 (4th ed.) for definitionsExample:

Example: Titanic Survival Count by Class

What would the relative frequency be (in %s)?

Bar Charts• A bar chart displays the distribution of a categorical variable,

showing the counts for each category next to each other for easy comparison.

• A bar chart stays true to the area principle.

• Thus, a better display for the ship data is this as opposed to…

Dotplots• A dotplot is a simple

display. It just places a dot along an axis for each case in the data.

• The dotplot to the right shows Kentucky Derby winning times, plotting each race as its own dot.

• You might see a dotplot displayed horizontally or vertically.

Use for small numerical (sometimes categorical) data sets.

HOMEWORK

Pg.18: #1.12, 1.13, 1.14, 1.17, 1.20, 1.21, 1.24

Quiz 1.1-1.4