Chapter 2 - Using Graphs to Visualize Data - Part 1

Statistics are divided into two main branches

1. WHAT

2. WHAT

Statistics are divided into two main branches

1. Inferential statistics

2. Descriptive statistics

Inferential statistics

A set of techniques that use the laws of chance and probability to help researchers understand the meaning of their data and the inferences they can make from those data

Descriptive statistics

Organizes and summarizes the properties of a dataset without any inferential analysis

There are two ways of conveying descriptive statistics

1. WHAT

2. WHAT

There are two ways of conveying descriptive statistics

1. Graphs

2. Numbers

Data can be

• WHAT

• WHAT

• WHAT

• WHAT

• WHAT

• WHAT

• WHAT

• WHAT

Data can be

• qualitative

• quantitative

• Continuous

• categorical

• nominal

• ordinal

• interval

• ratio

All graphs with two perpendicular lines is called WHAT - singular is WHAT 

All graphs with two perpendicular lines is called AXES - singular is AXIS 

X-axis

Horizontal axis running along the bottom of the graph - identifies the variable you are counting or measuring 

Y-axis

Vertical axis on the left side of the graph - Explains how those variables are presented 

The two axes intersect at the WHAT 

The two axes intersect at the ORIGIN 

You can summarize data in two ways

1. WHAT

2. WHAT

You can summarize data in two ways

1. Statistical values

2. Data distribution 

Data distribution

For a given variable, a data visualization containing the frequency of all possible responses on the Y-axis and all possible responses on the X-axis. (ex, Graph)

Statistical values

numerical values that summarize, describe, or help draw conclusions from a set of data (ex, average)

Frequency

Specifies how often a particular response was given or obtained for a variable 

Relative frequency / relative percent

The frequency of a response divided by the total number of participants 

Frequency table

Presents frequency data for participants’ responses for categorical data 

Frequency tables consist of WHAT and WHAT 

Frequency tables consist of ROWS and COLUMNS 

Columns

Vertical elements in a table 

Rows

Horizontal elements in a table 

What are the four types of graphs

1. WHAT

2. WHAT

3. WHAT

4. WHAT

What are the four types of graphs

1. Bar graphs

2. Histograms

3. Line graphs

4. Scatterplots

Bar graph

A data visualization in which the amount of a variable is typically represented on the Y-axis and the categories of interest are represented on the X-axis.

Bar graphs are usually illustrated as

1. WHAT

2. WHAT

Bar graphs are usually illustrated as

1. Categorical data counts

2. Average values for a continuous variable

Raw data

Unaltered by any statistical technique

Bar graphs are useful when displaying data from two different WHAT variables

Bar graphs are useful when displaying data from two different CATEGORICAL variables

Social norms

Unwritten rules that are in the back of our minds, guiding behaviour

Horizontal bar graphs

Bar graphs that use horizontal rather than vertical bars

Horizontal bar graphs are used to improve WHHAT or WHHAT

Horizontal bar graphs are used to improve READABILITY or AESTHETIC RESONS 

Stacked bar graph

Shows subcategories of the item being measured 

Bar graphs measure one or more WHAT variables

Bar graphs measure one or more CATEGORICAL variables

Histogram

a graphical display that shows the frequency distribution of continuous numerical data using adjacent, touching bars

In a histogram the variable may be measured across WHAT or within WHAT or WHAT

In a histogram the variable may be measured across TIME or within GROUPS or INTERVALS

Difference between a histogram and a bar graph: you can WHAT the bars in a bar graph, and the graph could still be interpreted easily, but if you reorder the bars in a histogram, you will miss important WHAT in the data 

Difference between a histogram and a bar graph: you can REORDER the bars in a bar graph, and the graph could still be interpreted easily, but if you reorder the bars in a histogram, you will miss important TRENDS in the data 

Histograms measure one or more WHAT variables

Histograms measure one or more CONTINUOUS variables

Line graph

uses points and lines to show how data changes over a continuous interval or time period

Line graphs are the same as a WHAT graph or a WHAT - researcher just chooses what they deem is the best to show the data 

Line graphs are the same as a BAR graph or a HISTOGRAM - researcher just chooses what they deem is the best to show the data 

Line graphs often display a unit of WHAT on the x-axis and the thing your WHAT on the y-axis

Line graphs often display a unit of TIME on the x-axis and the thing your MEASURING on the y-axis

Line graphs are useful for comparing WHAT trends over WHAT 

Line graphs are useful for comparing TWO trends over TIME 

Line graphs measure one or more WHAT variables

Line graphs measure one or more CONTINUOUS variables

Scatterplot

Includes multiple dots, with each dot illustrating two continuous variable scores for each participant or case 

Each dot in a scatterplot represents a WHAT of scores that belong WHAT 

Each dot in a scatterplot represents a PAIR of scores that belong TOGETHER 

Linear relationship

two variables appear to be related, the dots in the scatterplot will converge on a sloped line, indicating an association between the two variables

Scatterplots are different from bar graphs and histograms in which scatterplots use both WHAT to measure two WHAT variables

Scatterplots are different from bar graphs and histograms in which scatterplots use both AXES to measure two DIFFERENT CONTINUOUS variables