-
8/11/2019 Distribusi Frekuensi M
1/20
Frequency Distribution
-
8/11/2019 Distribusi Frekuensi M
2/20
A frequency distribution is a is a grouping of
data into mutually exclusive categories showingthe number of
observations in each class..
Two types frequency distributions are:1. Numerical
Frequency distribution that has quantitative group
in each class.
2. CategoricalFrequency distribution that has qualitative
groupin each class.
-
8/11/2019 Distribusi Frekuensi M
3/20
Determining the question to be addressed
Constructing frequency distribution is a part in describedatas
the we collect.
-
8/11/2019 Distribusi Frekuensi M
4/20
Determining the question to be addressed
Collecting raw data
-
8/11/2019 Distribusi Frekuensi M
5/20
Determining the question to be addressed
Collecting raw data
Organizing data (frequency distribution)
-
8/11/2019 Distribusi Frekuensi M
6/20
Determining the question to be addressed
Collecting raw data
Organizing data (frequency distribution)
Presenting data (graph)
-
8/11/2019 Distribusi Frekuensi M
7/20
Determining the question to be addressed
Collecting raw data
Organizing data (frequency distribution)
Presenting data (graph)
Drawing conclusions
-
8/11/2019 Distribusi Frekuensi M
8/20
Terminologies in Frequency Distribution
Class Limit : Numbers that separate between twoclasses. Two
kinds are lower class and upper class.
Class Frequency : The number ofobservations in each class.
Class Boundary : A midpoint between alower class limit and upper
class limit forthe previous class.
-
8/11/2019 Distribusi Frekuensi M
9/20
Weekly Earnings Number of
Employees, f
301 400 9401 500 16501 600 33601 700 20
701 800 14
801 900 8
Total number of employees 100
Fifth class
Lower limit ofthe sixth class
Upper limit ofthe sixth class
Frequency ofthe third class
Classboundary ?
-
8/11/2019 Distribusi Frekuensi M
10/20
Class Midpoint : A point that divides a class intotwo equal
parts. This is the average of the upperand lower class limits.
Open Class : Classthat have no upper
limit.
Class interval : The classinterval is obtained bysubtracting the
lower limit ofa class from the lower limit ofthe next class. The
classintervals should be equal.
-
8/11/2019 Distribusi Frekuensi M
11/20
Weekly Earnings Number ofEmployees
301 400 9401 500 16501 600 33
601 700 20
701 800 14
801 900 8
Total number of employees 100
Midpoint is (301+400)/2 = 350,5
Class Interval is?
Class Interval is?
-
8/11/2019 Distribusi Frekuensi M
12/20
A Relative Frequency Distribution shows the percent
ofobservations in each class.
Cumulative Frequency Distribution is used todetermine how many
or what proportion of the data
values are below or above a certain value.
-
8/11/2019 Distribusi Frekuensi M
13/20
WeeklyEarnings
Number ofEmployees Relative
frequencyCommulativefrequency
301 400 9 9/100 9
401 500 16 16/100 25
501
600 33 33/100 58601 700 20 20/100 78
701 800 14 14/100 92
801 900 8 8/100 100
Total number ofemployees
100 1
-
8/11/2019 Distribusi Frekuensi M
14/20
The three commonly used graphic forms areHistograms, Polygons ,
and a Cumulative
Frequency distribution.
A Histogram is a graph in which the class midpoints orlimits are
marked on the horizontal axis and the classfrequencies on the
vertical axis.The class frequencies are represented by the heights
of thebars and the bars are drawn adjacent to each other.
0
2
4
6
8
10
12
14
10 15 20 25 30 35
Hours spent studying
F r e q
u e n c y
-
8/11/2019 Distribusi Frekuensi M
15/20
A Frequency Polygon consists of line segmentsconnecting the
points formed by the class midpoint
and the class frequency.
0
2
4
6
8
10
12
14
10 15 20 25 30 35
Hours spent studying
F r e q u e n c y
-
8/11/2019 Distribusi Frekuensi M
16/20
Construct frequency distribution
1. Sort raw data in ascending order2. Decide on the number of
classes using the formula
k = 1 + 3,322 log n
where k=number of classes
n=number of observations3. Determine the class interval or width
using the
formula
4. Set the individual class limits
5. Tally and count the number of items in each class.
H Lk
-
8/11/2019 Distribusi Frekuensi M
17/20
6. Construct the frequency distribution and complete withclass
midpoint, relative frequency, and CumulativeFrequency
Example: A manufacturer of winter coatrandomly selects 20 winter
days andrecords the daily temperature.
24, 35, 17, 21, 24, 37, 26, 46, 58, 30,
32, 13, 12, 38, 41, 43, 44, 27, 53, 27
1. Sort raw data in ascending order:
-
8/11/2019 Distribusi Frekuensi M
18/20
2. Class number : 3. Class interval :
4. Set the individual class limit and construct thefrequency
distribution
Interval Tally Fi Midpoint
Total 20 20 1
RelativeFrequency
-
8/11/2019 Distribusi Frekuensi M
19/20
IntervalCumulative
Frequency Cumulative
Frequency Frequency
-
8/11/2019 Distribusi Frekuensi M
20/20
Histogram: Daily High Temperature
0
00
0
F r e q u e n c y
