Page 41 - DECO504_STATISTICAL_METHODS_IN_ECONOMICS_ENGLISH

Unit 3: Classification and Tabulation of Data: Frequency and Cumulative Frequency Distribution

• The body of the table must be as comprehensive as possible, consistent with the purpose. Notes
Unnecessary details must be avoided and, items in ‘miscellaneous or unclassified columns
must be least.
• Tabulation is an art which requires common sense in planning a table and viewing the proposed
table from the point of view of the user or the other person. Tabulation is done keeping in mind
the purpose of statistical investigation. The rules of tabulation act as guides in preparing a
good table.
• Quantitative classification data is done through seriation of data. If two variable quantities are
arranged side by side so that the measurable differences in the one correspond to the measurable
differences in the other, the result is formation of a statistical series.
• In continuous frequency distribution data are divided into class intervals instead of individual
values (as is done in case of discrete frequency distribution) class intervals can be formulated
like marks from 0 to 10, 10 – 20 and so on.
• Tables are nor prepared with the help of machines which may be either hand-operated or are
operated with electricity. Use of ‘needle sorting’ is one such machine for tabulation. Similarly
‘Punch Cards’ are also used. The work by these machines is more fast, easy and accurate.
• The most important method of organising and summarising statistical data is by constructing
a frequency distribution table. In this method, classification is done according to quantitative
magnitude. The items are classified into groups or classes according to their increasing order in
terms of magnitude and the number of items falling into each group is determined and indicated.
• Consider the number of all observations which are less than the upper class boundary of a given
class interval; this number is the sum of the frequencies upto and including that class to which
the upper class boundary corresponds.
• The cumulative frequency distribution is represented by joining the points obtained by plotting
the cumulative frequencies along the vertical axis and the corresponding upper class boundaries
along the x-axis. The corresponding polygon is known as cumulative frequency polygon (less
than) or ogive. By joining the points by a freehand curve we get the cumulative frequency
curve (“less than”). Similarly we can construct another cumulative frequency distribution (“more
than” type) by considering the sum of frequencies greater than the lower class boundaries of
the classes.
3.6 Key-Words

1. Tabulation of data : The process of placing classified data into tabular form is known as
tabulation. A table is a symmetric arrangement of statistical data in
rows and columns. Rows are horizontal arrangements whereas
columns are vertical arrangements. It may be simple, double or
complex depending upon the type of classification.
2. Frequency distribution : In statistics, a frequency distribution is an arrangement of the values
that one or more variables take in a sample. Each entry in the table
contains the frequency or count of the occurrences of values within a
particular group or interval, and in this way, the table summarizes
the distribution of values in the sample.
3.7 Review Questions

1. What do you mean by Tabulation ? What are the objectives and advantages of tabulation?
2. What is the frequency distribution ? Explain how it is formed from raw data.
3. Describe the importance of classification and tabulation in statistical analysis.
4. Describe the various points to be considered in the construction of a frequency table.
5. What are the different parts of a table ? What points should be taken into account while preparing
a table ?

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