Organization of Data
1. Classification of Data: The process of grouping data according to their characteristics is known as classification of data.
2. Objectives of Classification:
a] To simplify complex data
b] To facilitate understanding
c] To facilitate comparison
d] To make analysis and interpretation easy.
e] To arrange and put the data according to their common characteristics.
3. Statistical Series: Systematic arrangement of statistical data
I. Can be on the basis of individual units :
The data can be individually presented in two forms:
i] Raw data: Data collected in original form.
ii] Individual Series: The arrangement of raw data individually. It can be expressed in two ways.
a] Alphabetical arrangement : Alphabetical order
b] Array: Ascending or descending order.
II. Can be on the basis of Frequency Distribution:
Frequency distribution refers to a table in which observed values of a variable are classified according to their numerical magnitude.
1. Discrete Series: A variable is called discrete if the variable can take only some particular values.
2. Continuous Series: A variable is called continuous if it can take any value in a given range. In constructing continuous series we come across terms like:
a] Class : Each given internal is called a class e.g., 0-5, 5-10.
b] Class limit: There are two limits upper limit and lower limit.
c] Class interval: Difference between upper limit and lower limit.
d] Range: Difference between upper limit and lower limit.
e] Mid-point or Mid Value: Upper limit - Lower limit
2
f] Frequency: Number of items [observations] falling within a particular class.
i] Exclusive Series: Excluding the upper limit of these classes, all the items of the class are included in the class itself. E.g., :
Marks | 0-10 | 20-Oct | 20-30 | 30-40 |
Number of Students | 2 | 5 | 2 | 1 |
ii] Inclusive Series: Upper class limits of classes are included in the respective classes. E.g.,
Marks | 0-9 | 19-Oct | 20-29 |
Number of Students | 2 | 5 | 2 |
Open End Classes : The lower limit of the first class and upper limit of the last class are not given. E.g.,
Marks | Below 20 | 20-30 | 30-40 | 40-50 | 50 and above |
Number of Students | 7 | 6 | 12 | 5 | 3 |
iii] Cumulative Frequency Series: It is obtained by successively adding the frequencies of the values of the classes according to a certain law.
a] ‘Less than’ Cumulative Frequency Distribution :
The frequencies of each class-internal are added successively.
b] ‘More than’ Cumulative Frequency Distribution:
The more than cumulative frequency is obtained by finding the cumulative totals of frequencies starting from the highest value of the variable to the lowest value.
Marks | No. of Students |
0-10 | 2 |
10-20 | 5 |
20-30 | 10 |
30-40 | 12 |
40-50 | 17 |
50-60 | 4 |
Marks | No. of Students |
Less than 10 | 2 |
Less than 20 | 7 |
Less than 30 | 17 |
Less than 40 | 29 |
Less than 50 | 46 |
Less than 60 | 50 |
Marks | No. of Students |
More than 0 | 50 |
More than 10 | 48 |
More than 20 | 43 |
More than 30 | 33 |
More than 40 | 21 |
More than 50 | 4 |
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