Chapter 2-- Frequency Distributions and Graphs

Array

An ordering of every attributes of a variable that occurred within the raw data set, from the lowest or smallest to the highest or largest.

bar graph

Bars are equal width The bars are not allowed to touch The height of each bar reflects the frequency of the attribute A comparison of the frequency for different attributes is implicit, or in other words, if a bar of one length represents the frequency of an attribute, a bar twice as long represents a frequency twice as large for another attribute. Categories are emphasized

Cumulative Frequency Distribution

Constructed as if the data generated for a variable are at the ordinal or higher level of measurement

Absolute Frequency Distribution (simple frequency)

Constructed by counting the number of times each attribute occurred and place this total next to that attribute

Percentage Frequency Distribution

Display an absolute percentage column on the far right-hand side.

Percentile Ranks (percentiles)

Indicate the percentage of cases within a group who attribute falls below a particular score.

Meaningful grouping

It is a grouping that reduces the number of attributes to a reasonably small number that can be easily displayed and, more importantly, understood while not losing any more measurement precision than is necessary.

Stem-and-leaf plot

Makes it possible to visually see all the actual individual attributes in the distribution of a variable

Grouped Cumulative Percentage Distribution

Provides a good overview

Point of origin

The point at which the x-axis and y-axis meet.

Grouped Frequency Distribution

Use groupings in the first column instead of using the clients' actual ages, or attributes.

Graphs

Used to communicate the "bigger picture" Convey information easily to the user They highlight salient features of the data They can show relationships not obvious from studying a list of numbers

Data visualization tools

Vennage Piktochart Tableau Circos

Frequency Polygon

Visual of interval or ratio-level data Connects lowest and highest attributes Used to understand the shapes of distributions A curved shape, a kind of picture, that reflects the overall distribution of the attributes of a variable within a data set.

Pie Charts

Visual of nominal level data Divided into sectors that each represent category It is a really good way to show relative sizes Can be used to show percentages of a whole

Histograms

Visual of ordinal or higher-level data Bars are touching Cannot be used with nominal level data Uses the height of the bar to reflect the frequency of an attribute for a given variable Rank order determines sequence.

Frequency Distribution

a table or graph that presents the number of times with which different values of a variable occur in a group of observations.

x-axis

abscissa

y-axis

ordinate