Vision of AIUB:

To promote professional and To promote professional and excellent leadership catering excellent leadership catering to the technological progress to the technological progress and development needs of the and development needs of the countrycountry

Meaning of StatisticsMeaning of Statistics

Statistics is as old as human Statistics is as old as human civilizationcivilization

The word statistics have been The word statistics have been derived from the Latin word derived from the Latin word StatusStatus

Or the Latin word Or the Latin word StatistStatistOr the German word Or the German word StatistikStatistikOr the French word Or the French word StatistiqueStatistique

Meaning of StatisticsMeaning of StatisticsThe word Statistics has three different The word Statistics has three different meanings:meanings:First: First: Statistics is the quantitative Statistics is the quantitative information of any inquiry.information of any inquiry.For Example: the statistics of birth and For Example: the statistics of birth and death, the statistics of export and death, the statistics of export and import, the statistics of input and output import, the statistics of input and output of any industry, the statistics of of any industry, the statistics of manpower, the statistics of loss and manpower, the statistics of loss and profit of different organizations, prices of profit of different organizations, prices of commodities etc…commodities etc…

Meaning of StatisticsMeaning of StatisticsSecond: Second: It is the scientific technique of It is the scientific technique of collection, analysis, and interpretation of collection, analysis, and interpretation of quantitative data.quantitative data.

For example: the method of collection of For example: the method of collection of data related to birth and family planning data related to birth and family planning adoption and then interpretation adoption and then interpretation regarding population growth. Collection of regarding population growth. Collection of data on cost and benefit of an industry and data on cost and benefit of an industry and interpretation for future development interpretation for future development after analyzing the collected data…after analyzing the collected data…

Meaning of StatisticsMeaning of Statistics

Third: Third: It is also used in singular It is also used in singular sense to explain the population sense to explain the population unknown characteristic by a unknown characteristic by a function of sample observations. function of sample observations. Such function is known as Such function is known as “Statistic”.“Statistic”.

What is Statistics?What is Statistics?Statistics - a set of concepts, rules, Statistics - a set of concepts, rules, and procedures that help us to:and procedures that help us to:organize numerical information in organize numerical information in the form of tables, graphs, and the form of tables, graphs, and charts; charts; understand statistical techniques understand statistical techniques underlying decisions that affect underlying decisions that affect our lives and well-being; and our lives and well-being; and make informed decisions. make informed decisions.

What is Statistics?What is Statistics?

Statistics may be defined as Statistics may be defined as the science which helps in the science which helps in evaluating the reliability of evaluating the reliability of observed phenomena. It thus observed phenomena. It thus contains: contains:

MathematicsMathematicsLogic andLogic andCommon senseCommon sense

Statistical MethodsStatistical MethodsThe numerical data have some The numerical data have some characteristics. The method which is characteristics. The method which is used to express these characteristics is used to express these characteristics is known as statistical methods or simply known as statistical methods or simply statistics.statistics.

Statistical methods reduce complex data Statistical methods reduce complex data to a simple representative number easily to a simple representative number easily adaptable to human mind and following adaptable to human mind and following are the major aspects of statistical are the major aspects of statistical methods:methods:

Statistical MethodsStatistical Methods(i)(i) Statistics enables realization of Statistics enables realization of

magnitudesmagnitudes(ii)(ii) Statistics enlarges individual Statistics enlarges individual

experiencesexperiences(iii)(iii) Statistics compares the simplified data Statistics compares the simplified data

and measures their relationshipand measures their relationship(iv)(iv) Statistics guides in the formation of Statistics guides in the formation of

policiespolicies(v)(v) Statistics tests the laws of other sciencesStatistics tests the laws of other sciences

Types Types ofof Statistics Statistics

Statistics deals with both statistical Statistics deals with both statistical data and statistical methods.data and statistical methods.

Statistical methods are again Statistical methods are again divided into two sub-fields, such as:divided into two sub-fields, such as:

Descriptive Statistics and Descriptive Statistics and Inferential Statistics…Inferential Statistics…

Types of StatisticsTypes of StatisticsDescriptive Statistics:Descriptive Statistics: Deals with collection, tabulation, Deals with collection, tabulation,

presentation and analysis of data.presentation and analysis of data. The study of frequency distribution is an The study of frequency distribution is an

aspect of tabulation.aspect of tabulation. The analytical aspects deal with the The analytical aspects deal with the

measures of central tendency, measures measures of central tendency, measures of dispersion.of dispersion.

All the above measures are used for uni-All the above measures are used for uni-variate; bi-variate and multi-variate data. variate; bi-variate and multi-variate data. The study of correlation, regression and The study of correlation, regression and association of attributes are included in association of attributes are included in the bi-variate descriptive statistics.the bi-variate descriptive statistics.

Descriptive StatisticsDescriptive Statistics: Methods of organizing, summarizing, and presenting data in an informative way.

EXAMPLE 1: A Gallup poll found that 49% of the people in a survey knew the name of the first book of the Bible. The statistic 49 describes the number out of every 100 persons who knew the answer.

EXAMPLE 2: According to Consumer Reports, General Electric washing machine owners reported 9 problems per 100 machines during 2001. The statistic 9 describes the number of problems out of every 100 machines.

Types of StatisticsTypes of Statistics

Inferential Statistics:Inferential Statistics:

The descriptive statistics are used for making The descriptive statistics are used for making predictions or decisions relating to predictions or decisions relating to unobserved characteristics. These decisions unobserved characteristics. These decisions involve statistical inference and the method of involve statistical inference and the method of taking decision is known as statistical taking decision is known as statistical inference.inference.

The inference is made by sampling, sampling The inference is made by sampling, sampling distribution, estimation of parameter and test distribution, estimation of parameter and test regarding any hypothesis on parameter.regarding any hypothesis on parameter.

Inferential Statistics:Inferential Statistics: A decision, estimate, prediction, or generalization about a population, based on a sample

A PopulationPopulation is a CollectionCollection of all possible individuals, objects, or measurements of interest.

A SampleSample is a portion, or part, of the population of interest.

Example 1: TV networks constantly monitor the popularity of their programs by hiring Nielsen and other organizations to sample the preferences of TV viewers.

Example 2: Wine tasters sip a few drops of wine to make a decision with respect to all the wine waiting to be released for sale.

Example 3: The accounting department of a large firm will select a sample of the invoices to check for accuracy for all the invoices of the company.

#1

Types of StatisticsTypes of Statistics(examples of inferential (examples of inferential

statistics)statistics)

Q u a lita t ive o r a ttrib u te(typ e o f c ar own ed )

d isc re te(n u m b er o f ch ild ren )

con tin u ou s(tim e taken fo r an exam )

Q u an tita tive o r n u m erica l

D A TA

Summary of Types of Summary of Types of VariablesVariables

Data?Data?A series of observation, measurement or facts. So A series of observation, measurement or facts. So to obtain data we have to measure or observe to obtain data we have to measure or observe something. This something is known as variable. something. This something is known as variable. For example, shoe size, weight and nationality are For example, shoe size, weight and nationality are all variables as we can obtain a series of all variables as we can obtain a series of observations or measurement for each of them:observations or measurement for each of them:VariableVariable Measurement of observationMeasurement of observationShoe sizeShoe size 6, 6 ½, 7, 7 ½6, 6 ½, 7, 7 ½WeightWeight 8.21 kg, 7.9 kg, 0.5 kg8.21 kg, 7.9 kg, 0.5 kgNationalityNationalityBritish, Canadian, BangladeshiBritish, Canadian, Bangladeshi

Variable TypesVariable Types

Two types:Two types:

QualitativeQualitative and and

Quantitative Quantitative

For a Qualitative Qualitative or Attribute VariableAttribute Variable the characteristic being studied is nonnumeric.

G ender E yeC olor

T ype of carState of

B irth

Types of Types of Variables Variables

In a Quantitative VariableQuantitative Variable information is reported numerically.

Types of Types of Variables Variables

Balance in your checking account

Minutes remaining in class

Number of children in a family

A Continuous VariableContinuous Variable can assume any value within a specified range.

The pressure in a tireThe pressure in a tire

The weight of a pork chopThe weight of a pork chop

The height of students in The height of students in a class. a class.

Types of Variables Types of Variables

There are four levels of data

Nominal Nominal OrdinalOrdinalIntervalIntervalRatioRatio

Levels of MeasurementLevels of Measurement

Nominal levelNominal level Data that is classified into categories and cannot be arranged in any particular order.

G ender

E yeC olor

Nominal dataNominal data

Nominal level variables must be:

Mutually exclusiveMutually exclusive An individual, object, or measurement is included in only one category.

Exhaustive Exhaustive Each individual, object, or measurement must appear in one of the categories.

Levels of MeasurementLevels of Measurement

Ordinal levelOrdinal level: involves data arranged in some order, but the differences between data values cannot be determined or are meaningless.

During a taste test of 4 soft drinks, Coca Cola was ranked number 1, Dr. Pepper number 2, Pepsi number 3, and Root Beer number 4.

1

2

3

4

Levels of MeasurementLevels of Measurement

Interval levelInterval level Similar to the ordinal level, with the additional property that meaningful amounts of differences between data values can be determined. There is no natural zero point.

Temperature on the Fahrenheit scale.

Ratio level:Ratio level: the interval level with an inherent zero starting point. Differences and ratios are meaningful for this level of measurement.

M iles traveled by salesrepresentative in a month M onthly income

of surgeons

Importance of StatisticsImportance of StatisticsThe explanation of statistical methods gives The explanation of statistical methods gives us an idea that statistics is indispensable for us an idea that statistics is indispensable for a clearer appreciation of any problem a clearer appreciation of any problem affecting the welfare of mankind.affecting the welfare of mankind.Problem relating to national development, Problem relating to national development, education, health care, law and order education, health care, law and order situation, industrial development, situation, industrial development, development in economics and business, development in economics and business, unemployment, poverty, food shortages, unemployment, poverty, food shortages, communication cannot solved without proper communication cannot solved without proper statistical investigation.statistical investigation.

Importance of StatisticsImportance of StatisticsThe importance of statistics:The importance of statistics:The statistics of wealth and manpower are The statistics of wealth and manpower are important for development planning.important for development planning.Statistics are invaluable in business and Statistics are invaluable in business and commerce.commerce.An economist can study the phenomena of An economist can study the phenomena of changes the value of currency to prices, the changes the value of currency to prices, the influence of wages on efficiency of labor.influence of wages on efficiency of labor.Statistics helps the planner to estimate the Statistics helps the planner to estimate the revenue income and expenditure of the revenue income and expenditure of the country for the ensuring year…country for the ensuring year…

Importance of StatisticsImportance of StatisticsStatistics helps the planners and administrators Statistics helps the planners and administrators for formulate rules and regulations to rule the for formulate rules and regulations to rule the country peacefully.country peacefully.Statistical studies of price and harvest time of Statistical studies of price and harvest time of agricultural products help the famer and buyer to agricultural products help the famer and buyer to plan for future action.plan for future action.Statistical studies help the industrialist to Statistical studies help the industrialist to enlarge the establishment efficiently and enlarge the establishment efficiently and economically.economically.The phenomena related to physical, medical, The phenomena related to physical, medical, geological, zoological, meteorological may not geological, zoological, meteorological may not estimated and predicated with reliable accuracy estimated and predicated with reliable accuracy depending on probability theory…depending on probability theory…

Importance of StatisticsImportance of StatisticsThe entire insurance business resets on the The entire insurance business resets on the compilation of life tables and computation of compilation of life tables and computation of expectation of life from time to time.expectation of life from time to time.Export and import business rests on the Export and import business rests on the study of supply and demand of commodities.study of supply and demand of commodities.A stock exchange broker or an investor in A stock exchange broker or an investor in securities needs knowledge of interest rates, securities needs knowledge of interest rates, the fluctuation of investment market and the fluctuation of investment market and other related information to succeed in his ir other related information to succeed in his ir her business.her business.

Scope of StatisticsScope of Statistics To plan for a welfare state, it is of primary To plan for a welfare state, it is of primary

importance to collect information on different importance to collect information on different aspects of human life and to analyze the collected aspects of human life and to analyze the collected information for the purpose of framing suitable information for the purpose of framing suitable policies.policies.

The information on population aspects may be The information on population aspects may be obtained from the registration of vital statistics obtained from the registration of vital statistics and from the population census data.and from the population census data.

Statistical data relating to prices, production, Statistical data relating to prices, production, consumption, income and expenditure, investment consumption, income and expenditure, investment and profits are extensively used for the and profits are extensively used for the development and planning of industry…development and planning of industry…

Scope of StatisticsScope of Statistics Data on index number, time series analysis, Data on index number, time series analysis, demand analysis, cost analysis, forecasting etc are demand analysis, cost analysis, forecasting etc are used for economic polices.used for economic polices.Agricultural census data provide information for Agricultural census data provide information for formulating scientific plan on agriculture.formulating scientific plan on agriculture.Sound population policy depends on statistics of Sound population policy depends on statistics of births, deaths, the distribution of population by age, births, deaths, the distribution of population by age, sex and area, family planning activities, marriage sex and area, family planning activities, marriage and divorces etc.and divorces etc.Mortality statistics, incidence of diseases, number Mortality statistics, incidence of diseases, number of death by age are of paramount interest to health of death by age are of paramount interest to health authorities…authorities…

Scope of StatisticsScope of Statistics Statistical survey on livestock provides Statistical survey on livestock provides

information for formulating policy on information for formulating policy on livestock population. It will also help in livestock population. It will also help in planning to get increased animal protein.planning to get increased animal protein.

National policy on import and export of National policy on import and export of agricultural crops needs data on agricultural crops needs data on production, consumption of different types production, consumption of different types of crops for a certain period of time.of crops for a certain period of time.

Limitation of StatisticsLimitation of StatisticsStatistics does not deal with qualitative Statistics does not deal with qualitative phenomena. However, qualitative phenomena phenomena. However, qualitative phenomena can be analyzed if it is expressed numerically or can be analyzed if it is expressed numerically or if it is scored after assigning appropriate if it is scored after assigning appropriate number.number.Statistics deal with population and statistical Statistics deal with population and statistical methods deals with mass of data and not with a methods deals with mass of data and not with a single figure.single figure.Statistical laws are not exact and all are Statistical laws are not exact and all are inferences are drawn with a certain level of inferences are drawn with a certain level of accuracy based on probability…accuracy based on probability…

Limitation of StatisticsLimitation of Statistics Statistics can be misused. The data placed in Statistics can be misused. The data placed in

the hands of an inexpert may lead to be the hands of an inexpert may lead to be compiled inaccurately, manipulated compiled inaccurately, manipulated deliberately and interpreted unscientifically, deliberately and interpreted unscientifically, the effect of which produce a false statistical the effect of which produce a false statistical argument.argument.

Statistics cannot prove anything. It plays an Statistics cannot prove anything. It plays an auxiliary role to summaries a fact.auxiliary role to summaries a fact.