1. lecture basic statistics (1)

7/30/2019 1. Lecture Basic Statistics (1)

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Vision of AIUB:

To promote professional and excellent

leadership catering to the technological

progress and development needs of the

country


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Meaning of Statistics

Statistics is as old as human civilization

The word statistics have been derivedfrom the Latin word Status

Or the Latin word Statist

Or the German word Statistik

Or the French word Statistique


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The word Statistics has three differentmeanings:

First: Statistics is the quantitative information

of any inquiry.For Example: the statistics of birth and death,

the statistics of export and import, the

statistics of input and output of anyindustry, the statistics of manpower, the

statistics of loss and profit of different

organizations, prices of commodities etc


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Second: It is the scientific technique of collection,

analysis, and interpretation of quantitative data.

For example: the method of collection of data

related to birth and family planning adoption and

then interpretation regarding population growth.

Collection of data on cost and benefit of an

industry and interpretation for future

development after analyzing the collected data


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Third: It is also used in singular sense to

explain the population unknown

characteristic by a function of sampleobservations. Such function is known as

Statistic.


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What is Statistics?

Statistics - a set of concepts, rules, andprocedures that help us to:

organize numerical information in the

form of tables, graphs, and charts;

understand statistical techniques

underlying decisions that affect our livesand well-being; and

make informed decisions.


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What is Statistics?

Statistics may be defined as the science

which helps in evaluating the reliability

of observed phenomena. It thuscontains:

Mathematics

Logic and

Common sense


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Statistical Methods

The numerical data have some characteristics. Themethod which is used to express these

characteristics is known as statistical methods or

simply statistics.

Statistical methods reduce complex data to a simple

representative number easily adaptable to humanmind and following are the major aspects of

statistical methods:


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Statistical Methods

(i) Statistics enables realization of magnitudes

(ii) Statistics enlarges individual experiences

(iii) Statistics compares the simplified data andmeasures their relationship

(iv) Statistics guides in the formation of policies

(v) Statistics tests the laws of other sciences


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Types ofStatistics

Statistics deals with both statistical data

and statistical methods.

Statistical methods are again divided into

two sub-fields, such as:

Descriptive Statistics and

Inferential Statistics


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Types of Statistics

Descriptive Statistics:

Deals with collection, tabulation, presentationand analysis of data.

The study of frequency distribution is an aspectof tabulation.

The analytical aspects deal with the measures ofcentral tendency, measures of dispersion.

All the above measures are used for uni-variate;

bi-variate and multi-variate data. The study ofcorrelation, regression and association ofattributes are included in the bi-variate

descriptive statistics.


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Descriptive 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 nameof the first book of

the Bible. The statistic

49 describes the

number out of every100 persons who knew

the answer.

EXAMPLE 2: According

to Consumer Reports,

General Electric washing

machine owners reported9 problems per 100

machines during 2001. The

statistic 9 describes the

number of problems outof every 100 machines.


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Types of Statistics

Inferential Statistics:

The descriptive statistics are used for making

predictions or decisions relating to unobservedcharacteristics. These decisions involve statisticalinference and the method of taking decision isknown as statistical inference.

The inference is made by sampling, samplingdistribution, estimation of parameter and test

regarding any hypothesis on parameter.


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Inferential Statistics:A decision, estimate,

prediction, or generalization about a

population, based on a sample

APopulationis aCollectionofall possibleindividuals,

objects, ormeasurements of interest.

ASampleis

a portion, orpart, of the

population

of interest


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Example 1: TV

networks constantly

monitor the

popularity of their

programs by hiring

Nielsen and other

organizations tosample the

preferences of TV

viewers.

Example 2: Wine

tasters sip a few drops

of wine to make adecision 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 theinvoices of the company.

#1

Types of Statistics

(examples of inferential statistics)


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For a Qualitative orAttribute Variable the characteristicbeing studied is nonnumeric.

Types of Variables


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In a Quantitative Variable information is reportednumerically.

Types of Variables

Balance in your checking account

Minutes remaining in class

Number of children in a family

Q i i i bl b l ifi d i h


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Quantitative variables can be classified as either

Discrete or Continuous.

Discrete Variables: can only assume

certain values and there are usually

gaps between values.

Example: the number

of bedrooms in a

house, or the numberof hammers sold at

the local Home Depot

(1,2,3,,etc).

Types of Variables


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AContinuous Variable can assume any valuewithin a specified range.

The pressure in a tire

The weight of a pork chop

The height of students in a class.

Types of Variables


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Qualitative or attribute

(type of car owned)

discrete

(number of children)

continuous

(time taken for an exam)

Quantitative or numerical

DATA

Summary of Types of Variables


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There are four levels ofdata

Nominal

OrdinalInterval

Ratio

Levels of Measurement


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Nominal levelData that is

classified into

categories and

cannot be arranged

in any particularorder.

Nominal data


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Nominal level variables must be:

Mutually exclusive

An individual, object, or

measurement is included in only

one category.

Exhaustive

Each individual, object, or

measurement must appear in one

of the categories.

Levels of Measurement

O di l l l


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Ordinal level: involves data arranged in some order, butthe 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 number2, Pepsi number

3, and Root Beer

number 4. Levels of Measurement


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Interval levelSimilar to the ordinal level, with the additional

property that meaningful amounts of differencesbetween data values can be determined. There isno natural zero point.


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Ratio level: the interval level with an inherent zerostarting point. Differences and ratios are meaningful

for this level of measurement.


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Importance of Statistics

The explanation of statistical methods gives us an

idea that statistics is indispensable for a clearer

appreciation of any problem affecting the welfare

of mankind.Problem relating to national development,

education, health care, law and order situation,

industrial development, development ineconomics and business, unemployment, poverty,

food shortages, communication cannot solved

without proper statistical investigation.


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Importance of StatisticsThe importance of statistics is thus be pointed out

as follows: The statistics of wealth and manpower are

important for development planning.

Statistics are invaluable in business andcommerce.

An economist can study the phenomena ofchanges the value of currency to prices, theinfluence of wages on efficiency of labour.

Statistics helps the planner to estimate therevenue income and expenditure of the country

for the ensuring year


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Statistics helps the planners and administratorsfor formulate rules and regulations to rule thecountry peacefully.

Statistical studies of price and harvest time of

agricultural products help the famer and buyerto plan for future action.

Statistical studies help the industrialist toenlarge the establishment efficiently and

economically. The phenomena related to physical, medical,

geological, zoological, meteorological may notestimated and predicated with reliable accuracy

depending on probability theory


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The entire insurance business resets on thecompilation of life tables and computation of

expectation of life from time to time.

Export and import business rests on the study ofsupply and demand of commodities.

A stock exchange broker or an investor in

securities needs knowledge of interest rates, thefluctuation of investment market and other

related information to succeed in his ir her

business.

S f S i i


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Scope of StatisticsTo plan for a welfare state, it is of primary

importance to collect information on different

aspects of human life and to analyze the collected

information for the purpose of framing suitable

policies.

The information on population aspects may be

obtained from the registration of vital statistics

and from the population census data.

Statistical data relating to prices, production,

consumption, income and expenditure,

investment and profits are extensively used for the

development and planning of industry


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Scope of Statistics

Data on index number, time series analysis,

demand analysis, cost analysis, forecasting etc areused for economic polices.

Agricultural census data provide information for

formulating scientific plan on agriculture. Sound population policy depends on statistics of

births, deaths, the distribution of population byage, sex and area, family planning activities,marriage and divorces etc.

Mortality statistics, incidence of diseases, numberof death by age are of paramount interest to

health authorities


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Scope of Statistics

Statistical survey on livestock providesinformation for formulating policy on livestockpopulation. It will also help in planning to get

increased animal protein.

National policy on import and export of

agricultural crops needs data on production,consumption of different types of crops for acertain period of time.


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Limitation of Statistics

Statistics does not deal with qualitativephenomena. However, qualitative phenomena

can be analyzed if it is expressed numerically or if

it is scored after assigning appropriate number. Statistics deal with population and statistical

methods deals with mass of data and not with a

single figure. Statistical laws are not exact and all are inferences

are drawn with a certain level of accuracy based

on probability


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Limitation of Statistics

Statistics can be misused. The data placed in the

hands of an inexpert may lead to be compiled

inaccurately, manipulated deliberately and

interpreted unscientifically, the effect of whichproduce a false statistical argument.

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

1. lecture basic statistics (1)

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