Textbook notes from Statistics for the Behavioural Sciences - applicable to spring or fall term
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frequency distribution: an organized tabulation of the number of individuals located
in each category on the scale of measurement. Allows experimenter to see how the
individual scores are distributed on a measurement scale.
> BASIC FD TABLES
First column: X (measurement categories) organized from highest lowest
Second column: f (frequency of occurrences of each category)
f = N
N = total number of individuals
TO FIND X from this: add each X value multiplied by its corresponding f
To find X2 from this: square each of the scores and add these values.
PROPORTION: measures fraction of total group that is associated with each score
Aka relative frequency.
Commonly appears as decimals.
Can be added as a 3rd column of a basic table, as p
p = f/N
PERCENTAGE: describe distributions of scores by associating each score with a
percentage of occurrences.
P(100)= f /N (100)
Can be included in a basic table, as %
> GROUPED FD TABLES
Used when the data set covers a v. wide range of values.
Class intervals: groups of scores (as opposed to individual values of the Basic FD
INTERVAL RULES (how to divide up range for max. clarity, usefulness, simplicity)
1.About 10 class intervals.
2.Width of each interval should be relatively simple
3.Bottom score in each should be a multiple of the width
4.All intervals should be same width
REAL LIMITS & FREQUENCY DISTRIBUTIONS