PSYC 243: CHAPTER 2- FREQUENCY DISTRIBUTIONS
20 Cards in this Set
| Front | Back |
|---|---|
|
Frequency Distribution
|
An organized tabulation of the number of individuals located in each category on the scale of measurement.
Can be a table or graph
|
|
Distribution presents the same two elements:
|
The set of categories that make up the original measurements
A record of the frequency, or number of individuals in each category
|
|
Proportion
|
Measures the fraction of the total group that is associated with each score
|
|
Percentage
|
Is associated with each score
First, find proportion than multiply by 100
|
|
Purpose for constructing a table:
|
To obtain a relatively simple, organized picture of data.
|
|
Grouped Frequency Distribution Table
|
This can be accomplished by grouping scores into intervals and then listing the intervals in the table instead of listing each individual score.
|
|
Class Intervals
|
Groups or intervals
|
|
Guidelines for Frequency Distribution Tables
|
The grouped frequency distribution table should have about 10 class intervals
The width of each interval should be a relatively simple number
The bottom score in each class interval should be a multiple of the width
All intervals should be the same width
|
|
Histogram
|
First list the numerical scores (the categories of measurement) along the X-axis. Then you draw a bar above each X values so that:
the height of the bar corresponds to the frequency of that category
for continuous variables, the width of the bar extends to the real limits of the catego…
|
|
Bar Graph
|
When the scores are measured on a nominal or ordinal scale (usually non-numerical values); the frequency distribution is displayed this way.
|
|
Smooth Curve
|
Indicates that you are not connecting a series of dots (real frequencies) but instead are showing the relative changes that occur from one score to the next.
|
|
Characteristics of a Distribution
|
shape
central tendency
variability
|
|
Central Tendency
|
Measures where the center of the distribution is located
|
|
Variability
|
Tells whether the scores are spread over a wide range or are clustered together
|
|
Shape
|
Is defined by an equation that prescribes the exact relationship between each X and Y value on the graph
|
|
Symmetrical distribution
|
It is possible to draw a vertical line through the middle so that one side of the distribution is a mirror image of the other
|
|
Skewed Distribution
|
The scores tend to pile up toward one end of the scale and taper off gradually at the other end.
|
|
Tail
|
The section where the scores taper off in a distribution
|
|
Positively Skewed
|
A skewed distribution with the tail on the right-hand side
|
|
Negatively Skewed
|
A skewed distribution with the tail on the left-hand side
|
PSYC 243: Test 3