Ch. 3: Frequency Distributions
I.
Frequency -
II. Distribution -
III. Frequency
Distribution -
A.
Ungrouped -
B. Grouped -
1. Find the Range
2. Determine Interval Width
3. List the Intervals
4. Tally the Scores and Sum into frequencies
C. Other Information that Can be Included in Frequency Distributions
1. Relative Frequencies -
2. Cumulative Frequencies -
3. Cumulative Percentage -
IV. Percentiles –
A.
cum fP
B.
XL
C.
Number of Scores into the Interval?
D.
Units into the Interval?
E.
Determine the Percentile Point
V. Percentile Rank –
A.
Find the Interval
B.
Scores in the Interval?
C.Convert to
scores per scale unit in the interval
D.Scores
between target score and lower real limit of the interval
E.
Multiply by the scores per scale unit
F.
Add to the number of scores below the interval
G.
Divide by total number of scores in the distribution (times
100 to convert it to a percentage)
VI. Graphing Frequency
Distributions
A. Axes
1. Vertical =
2. Horizontal =
3. Set intersection
4. Labeling is important
B.
Bar Graph -
C. Histogram -
D. Frequency Polygon -
1. Symmetrical -
2. Skewed -
a. Positively Skewed
b. Negatively Skewed
E.
Cumulative Percentage Curve -
F. Stem and Leaf
Diagrams