The word ‘data’ means information in the form of numerical figures or a set of given facts. For example, the percentage of marks scored by 10 pupils of a class in a test are: 36, 80, 65, 75, 94, 48, 12, 64, 88 and 98.
The set of these figures is the data related to the marks obtained by 10 pupils in a class test.
Types of Data
Statistics is basically the study of numerical data. It includes methods of collection, classification, presentation, analysis of data and inferences from data, Data as such can be qualitative or quantitative in nature. If one speaks of honesty. beauty, colour, etc., the data is qualitative while height, weight, distance, marks, etc., are quantitative. Data can also be classified as raw data and grouped data.
Data obtained from direct observation is called raw data. The marks obtained by 10 students in a monthly test is an example of raw data or ungrouped data. In fact, very little can be inferred from this data. So, to make this data clearer and meore meaningful, we group it nto ordered intervals.
To presenit the data in a more meaningful way. we condense the data into convenient number of classes or groups, generally not exceeding 10 and nor less than 5. This helps us in perceiving, at a glance, certain salient features of data.
Some basic definitions of data
Before getting nto the details of tabular representation of data, let us review some basic definitions:
Each numerical figure in a data is called an observation.
The mumber of times a partic ular observation occurs is called its frequency.
Tabulation or Presentation of Data
A systematical arrangement of the data in a tabular form 15 called tabulation or presentation of the data. This grouping results in a table called the frequency table which indicates the number of scores within each group.
Many conclusion about the characteristics of the data, the behavior of variables and etc., con be drawn from this table.
The quantitative data that is to be analyzed statically, can be divided into three categories.
- Individual series
- Discrete series
- Continuous series
Ayaw data that is collected form is an mdividual series
1. Runs scored by 6 batsmen in a test match: 13, 89, 56, 24, 48, and 17
2. Number of students in different classes in a school : 54, 46, 52, 38, 45, 50, 29, 60, 35, 56
A discrete series is formulated from the raw data by taking the frequency of the observation into consideration.
Example: Given below is the data showing the number of children in 10 families of locality : 1, 1, 2, 2, 3, 1, 2, 3, 2, 2
Arranging the data in the ascending order, we get 1, 1, 1, 2, 2, 2, 2, 2, 3, 3.
1, 1, 2, 2, 3, 1 , 2 , 3 , 2 , 2 , 1 , 1 , 2 , 2 , 2 , 2 , 2 , To count , we can use tally marks . We record tally marks in bunches of five, the fifth one crossing the other four diagonally, i.e.,
Continuous series formulates where frequencies are given along with the value of the variable in the from of class intervals. When the data contains large number of observations, we put them into different groups, called class intervals such as, 1-10, 11-20, 21-30, etc.