Chapter 1 Introduction to statistics, Definitions, scope and limitations.pptx

Statistics

1. Santosh marahatta Department of agronomy Agriculture and forestry university Rampur, chitwan , nepal Introduction to Statistics: Definitions, Scope and Limitations

2. Meaning and definition The term “statistics” is used in two senses: First in plural sense meaning a collection of numerical facts or estimates—the figure themselves . Secondly , as a singular noun , the term ‘statistics ’ denotes the various methods adopted for the collection, analysis and interpretation of the facts numerically represented. In singular sense, the term ‘statistics’ is better described as statistical methods . In our study of the subject, we shall be more concerned with the second meaning of the word ‘statistics ’.

3. Meaning and definition A.L . Bowley defines “Statistics may be called the science of counting”.  “ Statistics may be called the science of averages”.  According to King ,  “The science of statistics is the method of judging collective, natural or social, phenomenon from the results obtained from the analysis or enumeration or collection of estimates ”. In the words of Croxton & Cowden , “ Statistics may be defined as the collection, presentation, analysis and interpretation of numerical data”.

4. Meaning and definition Horace Secrist has defined “By statistics we mean aggregates of facts affected to a marked extent by a multiplicity of causes numerically expressed, enumerated or estimated according to reasonable standards of accuracy collected in a systematic manner for a pre-determined purpose and placed in relation to each other”. Statistic should possess the following characteristics . Statistics are aggregate of facts. A single weight of fingerling i.e. 20 or 30 g is not statistics, a series of weight are. Statistics are affected to a marked extent by a multiplicity of causes. A number of causes affect statistics in a particular field of enquiry, e.g., in production statistics are affected by climate , soil, fertility, availability of raw materials and methods of quick transport.

5. Meaning and definition Statistics are numerically expressed, enumrated or estimated. The subject of statistics is concerned essentially with facts expressed in numerical form (quantitative) but not qualitative descriptions. Statistics are numerated or estimated according to reasonable standard of accuracy. The figures should be counted or estimated according to reasonable standards of accuracy. Statistics should be collected in a systematic manner for a predetermined purpose. The statistical methods to be applied on the purpose of enquiry since data are always collected with some purpose. Statistics should be capable of being placed in relation to each other. The collected figure should be comparable and well-connected in the same department of inquiry.  Weight of fingerlings are to be compared only with the corresponding weight of fingerlings with different species, and not with , say, length of fingerlings.

6. Functions of statistics To present facts in a definite form :  Without a statistical study our ideas are likely to be vague, indefinite and hazy. To simplify unwieldy and complex data :   Complex data may be simplified by presenting them in the form of a table, graph or diagram, or representing it through an average etc. To use it as a technique for making comparisons :  The significance of certain figures can be better appreciated when they are compared with others of the same type. To enlarge individual experience :  An individual’s knowledge is limited to what he can observe and see. To provide guidance in the formulation of policies :  The purpose of statistics is to enable correct decisions, whether they are taken. To enable measurement of the magnitude of a phenomenon :  

7. Importance of statistics: some areas Planning is indispensable for better use of nation’s resources. Statistics are indispensable in planning and in taking decisions regarding export, import, and production etc., Statistics serves as foundation of the super structure of planning . Statistics helps the business man in the formulation of polices with regard to business . Statistical methods are applied in market and production research, quality control of manufactured products. Statistics is indispensable in economics . Any branch of economics that require comparison, correlation requires statistical data for salvation of problems. In collecting the information about population, military strength etc., Administration is largely depends on facts and figures thus it needs statistics

8. Bankers , stock exchange brokers, insurance companies all make extensive use of statistical data. Problems relating to poverty, unemployment, food storage, deaths due to diseases and shortage of food etc., cannot be fully weighted without the statistical balance. Thus statistics is helpful in promoting human welfare Statistics are a very important part of political campaigns as they lead up to elections . Statistics are used to calculate and illustrate the results in percentages and to calculate the margin for error . Thus Statistics plays an important role in our daily life, it is useful in almost all sciences – social as well as physical The statistical methods can be and are being followed by both educated and uneducated people In many instances we use sample data to make inferences about the entire population. Importance of statistics: some areas

9. In agriculture In determining the required doses of fertilizer for a particular crop and crop land. In estimating the losses incurred by particular pest and the yield losses due to insect, bird, or rodent pests statistics is used in entomology. In making data about decision on pesticides applications In determining and estimating the irrigation required by a crop per day, per base period. In soil chemistry also statistics helps classifying the soils basing on their analysis results, which are analyzed with statistical methods. Agricultural economists use forecasting procedures to determine the future demand and supply of food

10. In agriculture Animal scientists use statistical procedures to aid in analyzing data for decision purposes. Agricultural engineers use statistical procedures in several areas, such as for irrigation research, modes of cultivation and design of harvesting and cultivating machinery and equipment. Thus , In agricultural research, Statistical tools have played a significant role in the analysis and interpretation of data.

11. Statistics Descriptive statistics Inferential statistics Population Sample Study about the sample To describe about the population based on the information of sample Statistic : characteristics of sample, mean ( )   Parameter : characteristics of population, average ( )  

12. Limitations of Statistics Statistics does not study qualitative phenomenon Statistics does not study individuals Statistics laws are not exact laws Statistics does not reveal the entire information Statistics is liable to be misused Statistical conclusions are valid only on average base

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