Chapter 2- Investigating and Comparing Data Distributions

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Categorical Data:

Nominal Data:

Ordinal Data:

Numerical Data:

Continuous Data:

Discrete Data:

Frequency: A frequency table is a listing of the values a variable takes in a data set, along with how often (frequently) each value occurs.

Frequency can be recorded as a:

-frequency: the number of times a value occurs.

-percentage frequency: the percentage of times a value occurs, where:

percentage frequency = count ÷ total × 100%

-frequency distribution: a listing of the values a variable takes, along with how frequently each of these values occurs.

Bar charts:

In a bar chart:

-frequency or percentage frequency is shown on the vertical axis-the variable being displayed is plotted on the horizontal axis-the height of the bar (column) gives the frequency (or percentage)-the bars are drawn with gaps to indicate that each value is a separate category-there is one bar for each category.

Mode or Modal Category: It is the most frequently occurring category.

Histograms:

In a histogram:

-frequency (number or percentage) is shown on the vertical axis

-the values of the variable being displayed are plotted on the horizontal axis

-each column corresponds to a data value, or a data interval if the data is grouped;alternatively, for ungrouped discrete data, the actual data value is located at the middle of the column

-the height of the column gives the frequency (number or percentage).