Frequency Distribution
Frequency Distribution
(A) Introduction
1. Ungrouped data versus grouped data Ungrouped data (Raw data): It is a list of individual observed values of the random variable Grouped data (a frequency distribution): It is a table that displays the data in grouping along with the number of occurrences that fall into each group.
2. The components of a frequency distribution a. Class limits: They identify the inclusive values in a class of a frequency distribution The upper class limit (Lu) refers to the largest value that can go into any given class. The lower class limit (LL) refers to the smallest value that can go into any given class.
b. Class boundaries: They are the specific points along a measurement scale that separate adjoining classes. •A class boundary (Bu or BL) is the point halfway between the upper limit of one class and the lower limit of the next class.
•For discrete data, class boundaries are identical to class limits.
c. Class interval (i): It indicates the range of values included in each class. •It is the difference between the upper and lower boundaries values of each class
•It is the difference between the upper (lower) limit of one class and upper (lower) limit of the next class.
•It is the difference between the class midpoint of two successive classes.
d. Class midpoint (Class mark): It is the middle value of each class. The value of class mid-point can be determined by adding one-half of the class interval to the lower boundary of the class. X = BL + 0.5i
(B) Constructing a Frequency Distribution
1. To obtain the raw data.
2. To arrange the data set in the form of an array.
(An array is an arrangement of data in order of magnitude ---usually in ascending order..) 3. Determine the number of classes (k) to be used. 4. Determine the width of the class interval (i).
5. To make up a frequency table by sorting
(A) Introduction
1. Ungrouped data versus grouped data Ungrouped data (Raw data): It is a list of individual observed values of the random variable Grouped data (a frequency distribution): It is a table that displays the data in grouping along with the number of occurrences that fall into each group.
2. The components of a frequency distribution a. Class limits: They identify the inclusive values in a class of a frequency distribution The upper class limit (Lu) refers to the largest value that can go into any given class. The lower class limit (LL) refers to the smallest value that can go into any given class.
b. Class boundaries: They are the specific points along a measurement scale that separate adjoining classes. •A class boundary (Bu or BL) is the point halfway between the upper limit of one class and the lower limit of the next class.
•For discrete data, class boundaries are identical to class limits.
c. Class interval (i): It indicates the range of values included in each class. •It is the difference between the upper and lower boundaries values of each class
•It is the difference between the upper (lower) limit of one class and upper (lower) limit of the next class.
•It is the difference between the class midpoint of two successive classes.
d. Class midpoint (Class mark): It is the middle value of each class. The value of class mid-point can be determined by adding one-half of the class interval to the lower boundary of the class. X = BL + 0.5i
(B) Constructing a Frequency Distribution
1. To obtain the raw data.
2. To arrange the data set in the form of an array.
(An array is an arrangement of data in order of magnitude ---usually in ascending order..) 3. Determine the number of classes (k) to be used. 4. Determine the width of the class interval (i).
5. To make up a frequency table by sorting