Introduction and Importance of Statistics.

Croxton and Cowden defined statistics as the science of collection, presentation, analysis and interpretation of numerical data from the logical analysis.

For long time, Statistics was identified solely with the displays of data and charts pertaining to the economic, demographic, and political situations prevailing in a country.

Passive display of numbers and charts is now a minor aspect of statistics

What, then, are the role and principal objectives of statistics ????

Statistics deals with collecting informative data, interpreting these data, and drawing conclusions about a phenomenon under study.

The principles and methodology of statistics are useful in answering questions such as,

What kind and how much data need to be collected?

How can we analyze the data and draw conclusions?

How do we assess the strength of the conclusions and limit their uncertainty?

Certain terms

Data : Numerical information usually obtained by some process of measurement or counting, e.g., statistics of birth, deaths, data on milk, wool and egg production etc.

Population : A complete set of individuals, objects or measurements having some common observable characteristics. A population or universe consists of all possible values of a variable. Biologically, population can be defined as all the individuals of a given species found in a circumscribed area at a given time.

Sampling and Sample: The selection of a particular part of a population which can represent the whole population is known as sampling and the part selected is known as Sample.

Population: Population in statistics can be defined as the total number of individual observations from which we have to draw inferences.

Statistic : Measures such as Mean, Median, Mode etc., describing the characteristics of a sample are called Statistics.

Parameter : Any measures when they describe the characteristics of a population are called parameters.

Observation : Recording of information. It may be in the form of numerical assessment of an individual or object.

NOTE: It is conventional in statistics to use Greek letters for population parameters (e.g., m ,s ,s² ,r , b etc) and Roman letters for sample statistics (e.g. , `x, s, s², r, b, etc).

Variable : It is a character under observation whose value varies from individual to individual and from time to time in the same individual. Thus characteristics which show variation are called variables. A variable may also be defined as the property with respect to which individuals in a sample differ in some ascertainable way.

Variate : An individual observation of any variable is known as variate. When variable takes some value on the measuring scale, it is known as variate. It refers to a single reading, score, or observation of a given variable. These are identified by capital Roman letters, the most common symbol being used are X or Y. Thus X may stand say for body weight of animals. A variate will then refer to a given body weight; X _i being the body weight of the i^th animal, X₄ body weight of fourth animal, etc.

Qualitative and Quantitative variable: The individuals comprising the material under consideration are distinguished by some quality like flower colour etc. are known as qualitative variable similarly, the individuals who are distinguished by a measurement is known as quantitative variable.

MEANING OF STATISTICS

The word “statistics” is generally used in three different meanings,

•It means collection of numerical data that are to be analyzed and interpreted.

•It means the science of collecting, classifying and using the data. It involves the methods of analysis and interpretation of data known as “Statistical Methods/Applied Statistics”.

•It means the science that deals with the comprehensive explanation of statistical methods

Statistics encompasses,

•The design of study in order that it will reveal the most information efficiently,

•The collection of data,

•The analysis of data,

•The presentation of suitably summarized information, often in graphical or tabular form.

•The interpretation of the analysis in the manner which communicate the finding accurately

Strictly this broad numerical approach to biology is termed as BIOMETRY

Importance of statistics in Animal Science

1. To understand and to draw sound conclusions on research findings from literature and journals.

2. For planning of research experiments.

3. For assessment and correct interpretation of results from scientific studies.

4. For sample survey studies.

5. In order to study the effect of various factors on production performance of animals and to study the type of association between any two traits we must have the knowledge of statistics.

6. In other disciplines of animal and veterinary science like nutrition, pharmacology, medicine etc. the good knowledge of statistics is essential for preparation of scientific reports based on the experimental trials.

7. For planning, taking policy decisions and to draw valid and rational conclusions.

8. To measure uncertainty.

9. To study relationship between different phenomena.

10. To indicate trend behaviour.

11. To increase human experience.