# PSYC 210 Chapter Notes - Chapter 3: Exploratory Data Analysis, Bar Chart, Central Tendency

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**preview**shows page 1. to view the full**4 pages of the document.**Chapter 3

Displaying Data

•A collection of numbers has to be interpretable, they first must be organized in

some sort of logical order

3e.1. Plotting Data

•One of the simplest methods for reorganizing data is to make them more

intelligible is to plot them in some sort of graphical form

•Data can be represented graphically in several common ways

•Some of these methods are frequency distributions, histograms and stem-and-leaf

displays

Frequency Distributions

•As a first step we can make a frequency distribution = a distribution in which

the values of the DV are tabled or plotted against their frequency of occurrence

•Frequency distribution of the data is a way of organizing them in some sort of

logical order

•For example of reaction times, we would count the number of times that each

possible reaction time occurred

3.2. Stem-and-leaf displays

•A frequency distribution tells you how many times each value occurs and the

associated graph gives you a visual representation of the data

•A very nice way of retaining both the individual values and the frequency of those

values is by creating a stem-and-leaf display = graphical display presenting

original data arranged into a histogram

•Exploratory data analysis (EDA) = a set of techniques developed by John

Tukey for presenting data in visually meaningful ways

•One of the simplest methods is the stem-and-leaf display

•Leading digits = sometimes called the most significant digits are the leftmost

digits of a number (the tens)

•These leading digits form the stem = vertical axis of display containing the

leading digits

•Trailing digits = sometimes called the less significant are the digits to the right of

the leading digits

•Leaves = horizontal axis of display containing the trailing digits

Raw data Stem Leaf

0,1,1,2,2,3,4,4,4,5,5 0 01122344 …

10,11,11,12,17,16 1 01123333 …

oFirst row shows that there are 2 ones, 2 twos, etc.

oSecond row shows that there are 2 elevens, 1 twelve etc.

•From the stem-and-leaf display you could completely regenerate the raw data that

went into the display

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