Quantitative analysis for business decisions (QABD) |Unit 1 Introduction to statistics

 

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Quantitative analysis for business decisions

UNIT 1: 

INTRODUCTION TO STATISTICS 

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Meaning of Statistics

Statistics stands for the numerical information from which certain conclusions can be drawn.So the word statistics is used as "figures of numerical information".

Statistics stands for the collection,presentation,analysis and interpretation of numerical information.That is to collect,represent,analyse and draw valid conclusions on the basis of numerical data.

Definition of statistics according to Prof.Horace Secrist 

or Define statistics in plural sense    

(Same answer for both the questions)

Statistics in plural sense or as per Prof.Horace Secrist is  defined  as "the aggregate of facts affected to a marked extend by multiplicity of causes numerically expressed enumerated or estimated according to a reasonable standard of accuracy  collected in a systematic manner for a predetermined purpose and placed in relation to each other.

Mention any two functions of statistics  

• It presents the facts in a definite form
• It simplifies and condenses the size of the data
• It facilitates comparison
• It helps in formulating policies
• It helps in business forecasting

The features  or characteristics of statistics

• The statistics are aggregate of facts
• They are affected to a marked extend by multiplicity of causes
• Statistics are numerically expressed
• Statistics are estimated according to a reasonable standard of accuracy
• Statistics are collected in a systematic manner
• Statistics are collected for predetermined purpose
• Statistics must be placed in relation to each other

Limitations of Statistics

• It does not deal with individuals
• It does not deal with qualitative data
• Statistical laws are true only on an average
• Only experts can make best use of statistics
• For statistical analysis uniformity and homogeneity of data is essential.

Important Terminologies in Statistics

Data

A set of outcomes or possible observations that can be separated into two groups quantitative and qualitative.

Raw Data or Primary data

 Data which are collected for the first time directly from the field by the investigator is called primary data.They are original in nature.It is also called first hand data.

Primary data can be collected using the following methods:

• Direct personal observation
• Indirect oral interview
• Information through agencies
• Mailed questionnaires
• Schedules sent through enumerator

Secondary Data   

Secondary data is the data which has been already collected and analysed by enumerators.It is also called second hand data.

The sources of secondary data can be categorised as published sources or unpublished sources.

Population or universe

The totality of units under consideration is called population or universe.

A population which contains finite number of units is called finite population and that which contains infinite number of units is called infinite population.

Census

A census is a survey conducted on full set of observation objects belonging to a given population or universe.

Survey 

-A survey is an investigation about the characteristics of a given population by means of collecting data from  a sample of that population and estimating their characteristics through the systematic use of statistical methods.

Samples

The representative units of a population is called a sample.

Sample Survey

The representative units of a population is called a sample.An enumeration based on sample is called sample survey

Sampling

The process of extracting sample from the population is called sampling.The following methods are

• Simple random sampling
• Systematic sampling
• Stratified sampling

Parameter

A parameter is quantitative characteristic of the population that you are interested in estimating or testing

For eg. the mean or proportion of a population

 Units or individuals

The units whose characteristics are studied in any statistical survey are called units or individuals.

Variable

A quantitative characteristic which varies from unit to unit is called a variable.

Eg. Height/weight of students, number of students etc.

Attribute

A qualitative characteristic which varies from unit to unit is called as an attribute

Frequency

Frequency refers to the number of times an observation is repeated.In statistics the frequency of an event is the number of times the event occurred in the experiment or study.

 Discrete frequency distribution

A frequency distribution is a systematic presentation of the values taken by a variable along with their frequencies.While framing a frequency distribution if class intervals are not considered it is called discrete frequency distribution.

Continuous frequency distribution

While framing a frequency distribution if class intervals are  considered it is called discrete frequency distribution.

Classification of data

Classification is the process of arranging the data into groups or classes according to common characteristics possessed by the items of the data

Types of classification of data

1. Chronological (temporal) classification
2. Geographical  (spatial) classification
3. Qualitative classification 
4. Quantitative classification

1.Chronological classification

If the data is arranged over a  different period of time,then the type of classification is called chronological classification.

2.Geographical  classification

If the data is classified on the basis of geography location or area wise it is called geographical  classification

3.Qualitative classification 

If data is classified on the basis of the qualitative characteristics or attributes such as sex,literacy, employment ,religion etc it is called as qualitative classification 

4.Quantitative classification

the classification of units   on the basis of  quantitative  characteristic or variable such as height,weight,number of children etc is called as quantitative classification

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Quantitative analysis for business decisions