# DESCRIPTIVE AND INFERENTIAL STATISTICS

Statistics as a subject is very wide.  If consists of methods of handling massive data in a variety of problem situation. As you know, when used in singular sense, statistics is a study of the principles and methods used in the collection, presentation, analysis and interpretation of data in any sphere of enquiry. These methods and techniques are so diverse that statisticians generally categorise them into two:

1) descriptive statistics, and 2) inferential statistics.

Descriptive Statistics refer to various measures that are used to describe the characteristic features of the data. Such measures include measures of central tendency, measures of dispersion, etc. Graphs, tables and charts that display data are also examples of descriptive statistics. Suppose the number of first year B.Com. students is 100 and you compute the average marks of these students. Here you are using descriptive statistics. Similarly, when you are computing the average marks of a sample of 25 students from the same class but without attempting any generalisation about the entire class, you are still using descriptive statistics. Inferential Statistics on the other hand refer to statistical process of drawing valid inferences about the characteristics of population data on the basis of sample data. The word population in statistics does not mean only human population. It stands for totality of items related to any field of study. If the teacher, in the above example, decides to estimate the average marks of the entire class on the basis of the sample average, we would say that he is using

inferential statistics. It is not worthy that most of the time we use sample data to understand the features of the population data. Inferences about population drawn from sample measures may involve some error or discrepancy. The magnitude of such errors can be estimated on the basis of probability theory.

1) Are the following statements statistical data?

i) Weekly wages of 100 workers of a factory.

ii) Height of Ram is six feet.

iii) Mohan’s weight is 70 Kgs, Sohan’s height is 6.2 feet, and

Ram’s monthly income is Rs. 1,500.

iv) Sales of a company during the past 10 years.

2) Comment on the following statements in not more than one line.

i) Webster and Secrist defined descriptive statistics.

ii) Definition of statistics given by Yule and kendall is contained

in the one by Secrist.

iii) Qualitative data cannot be studied under statistics.

iv) Methods of statistics relate to collection and analysis of the

data only.

v) The definition of science of statistics by Bowley covers the

different stages of statistical methodology.

vi) Inferential statistics is related to the study of samples.