statistic intro

8/6/2019 Statistic Intro

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Meaning of Statistics

TermSTATISTICSderived from Latin wordSTATUSwhich meansPolitical State

In the 17th centuryProf. Gottfried Achenwallrecognized Statistics, a specialized branch ofhuman knowledge

The development of theory of probability

added importance for Statistics The development of Modern Statistics started

after Industrial revolution


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DIMENSION OF STATISTICS

The word Statistics is used in two

senses. Plural form :

Data (Values)

Singular form :

Science


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Definition of Statistics as a

Science

The collection, presentation,analysis and interpretation of

numerical data

by

Croxton andCowden


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Definition of Statistics

Aggregate of facts affected to a marked extentby multiplicity of causes, numerically expressed,

enumerated or estimated according toreasonable standards of accuracy, collected insystematic manner for a predetermined purposeand placed in relation to each other

By

Prof Horce Secrist


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Statistics are :

Aggregate of facts

Effected to a marked extent bymultiplicity of causes

Numerically expressed

Enumerated or estimated accordingto reasonable standards ofaccuracy

Collected in a systematic mannerfor a predetermined purpose


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Functions of Statistics

It simplifies complex data

It facilitates comparison

It facilitates the study relationshipbetween different facts

It enhances an individuals knowledge

It facilitates in formulation policies It tests the hypothesis

It facilitates forecasting


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Scope of Statistics

Statistics in

Business

Economics

Banking andFinance

Engineering

Medicine

Biology

Simply everywhere


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Limitations

Itd

eals with only quantitatived

ata It is true on an average only

It does not deal with an individual

It can mislead if it is handled by an in experiencedperson

Statistical results are correct only in general sense.For better results a large number of observationsrequired

Different results are obtained by different people

The laws of statistics are not exact like the laws ofsciences.

Statistics collected for a given purpose must beused for that purpose only.


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Comments on Statistics

Tons of Statistics will produce ounce of

truth

Statistics can prove any thing

There are three types of lies,- lies, damned

lies, Statistics


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Compliments

Without Statistics there is no life


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Data

Data are the factsand figures

thatare collected, summarized,

analyzed, and interpreted.

The data collected in a

particular study arereferred to

as the data set.


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Elements, Variables, and

Observations

Scales of Measurement

Qualitativeand Quantitative

Data

Cross-Sectional and Time Series

Data


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Theelementsare theentities onwhich dataare collected.

A variable isa characteristic ofinterest for theelements.

The set of measurements collectedfora particularelementis called an

observation. The total number of datavaluesin a

data setis the number ofelementsmultiplied by the number ofvaria

ble

s.


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, ,


Observations

ElementsElements

VariablesVariables

Data SetData Set DatumDatum

StockStock Annual Earn/Annual Earn/

CompanyCompany Exchange Sales($M) Sh.($)Exchange Sales($M) Sh.($)

DataramDataram AMEXAMEX 73.1073.10 0.860.86

EnergySouthEnergySouth OTCOTC 74.0074.00 1.671.67

KeystoneKeystone NYSENYSE 365.70365.70 0.860.86

LandCareLandCare NYSENYSE 111.40111.40 0.330.33

PsychemedicsPsychemedics AMEXAMEX 17.6017.60 0.130.13


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Nominal

Dataare labels or names used to

identify an attribute of theelement.

A nonnumeric label ora numeric

code may be used.


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Nominal

Example:

Students ofa university are classifiedby the school in which they areenrolled using a nonnumeric labelsuch as Business, Humanities,Education, and so on.

Alternatively, a numeric code couldbe used for the school variable (e.g. 1denotes Business, 2 denotesHumanities, 3 denotes Education, and

so on).


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Ordinal

The data have the properties of

nominal dataand the order orrankof the datais meaningful.

A nonnumeric label ora numeric

code may be used


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Ordinal

Example:

Students ofa university are classified

by their class standing using a

nonnumeric label such as Freshman,

Sophomore, Junior, orSenior.

Alternatively, a numeric code could

be used for the class standing

variable (e.g. 1 denotes Freshman, 2

denotesSophomore, and so on).


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Interval

The data have the properties of

ordinal dataand theintervalbetween observationsis

expressed in terms ofa fixed unit

of measure.

Interval dataarealways numeric.


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Interval

Example:

Melissa hasan SAT score of 1205,

while Kevin hasan SAT score of 1090.

Melissa scored 115 points more than

Kevin.


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Ratio

The data haveall the properties of

interval dataand theratio of twovaluesis meaningful.

Variables such as distance, height,weight, and time use theratio

scale. This scale must contain azero

value thatindicates that nothingexists for thevariableat thezero

point


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Ratio

Example:

Melissas collegerecord shows 36

credit hoursearned, while Kevins

record shows 72 credit hoursearned.

Kevin has twiceas many credit hours

earned as Melissa.


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Classification ofData

The process ofarranging the thingsingroups or classesaccording to theirresemblances

Modes of classification:1 Qualitative

2 Quantitative

3 Variable

4Discrete Variable

5 Continuous Variable6 Temporal

7 Spatial


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Descriptive statistics

Inferential statistics

Tools of Business Statistics


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DescriptiveStatistics Collect data

e.g. Survey, Observation,

Experiments

Present data

e.g. Charts and graphs

Characterize data

e.g. Sample mean = n

x i


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Types ofData

Quantitative

E.g..

Weight,

Length,

Tim

e,

Temperatureetc.


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Contd.

QualitativeData

E.g..

Kindness

Honesty

Sat

isf

act

ion

Perception etc.


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Inferential Statistics

D

rawing conclusions and/

or makingdecisions concerning a population

based only on sample data


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Data


Observations

Scales of Measurement

Qualitativeand Quantitative

Data

Cross-Sectional and TimeSeries

Data


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Dataand DataSets

Data are the factsand figures

thatare collected, summarized,

analyzed, and interpreted.

The data collected in a

particular study arereferred to

as the data set.


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Elements, Variables, andObservations

The elements are the entities on which data are

collected.

A variable is a characteristic of interest for theelements.

The set of measurements collected for a

particular element is called an observation.

The total number ofdata values in a data set is

the number of elements multiplied by the

number of variables.


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Data, DataSets,

Elements, Variables, and Observations

ElementsElements

VariablesVariables

Data SetData Set DatumDatum

StockStock Annual Earn/Annual Earn/

CompanyCompany Exchange Sales($M) Sh.($)Exchange Sales($M) Sh.($)

DataramDataram AMEXAMEX 73.1073.10 0.860.86

EnergySouthEnergySouth OTCOTC 74.0074.00 1.671.67

KeystoneKeystone NYSENYSE 365.70365.70 0.860.86

LandCareLandCare NYSENYSE 111.40111.40 0.330.33

PsychemedicsPsychemedics AMEXAMEX 17.6017.60 0.130.13


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Data Types

Data

Qualitative

(Categorical)

Quantitative

(Numerical)

Discrete Continuous

Examples:

M

arital Status Political Party

Eye Color

(Defined categories)Examples:

Number of Children

Defects per hour

(Counted items)

Examples:

Weight

Voltage

(Measured

characteristics)


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DataSources

Primary

Data Collection

SecondaryData Compilation

Observation

Experimentation

Survey

Print or Electronic


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Survey Design Steps Define the issue

what are the purpose and objectives of the

survey?

Define the population of interest

Formulate survey questions

make questions clear and

unambiguous use universally-accepteddefinitions

limit the number of questions


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Survey Design Steps

Pre-test the survey

pilot test with a small group of participants

assess clarity and length

Determine the sample size and sampling

method

Select Sample and administer the survey

(continued)


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Types of Questions

Closed-end Questions

Select from a short list ofdefined choices

Example: Major: __business __liberal arts

__science __other

Open-end Questions

Respondents are free to respond with any value, words, orstatement

Example: What did you like best about this course?

Demographic Questions

Questions about the respondents personal characteristics

Example: Gender: __Female __ Male


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DIAGRAMMATIC

REPRESENTATION

Presentation of data by using diagrams is

called Diagrammatic Representation

There are a large number of diagrammatic

which can be used for presentation of data.

The selection of particular diagram depend

upon the nature of data, objective ofpresentation


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Types ofDiagrams

DIAGRAMS

ONE DIMENSIONAL TWO DIMENSIONAL PICTOGRAMS CARTOGRAMS

1.Line diagram

2.Simple BarDiagram

3.Multiple BarDiagram

4.Sub-divided Bar

5.Percentage Bar

6. Pie-diagram


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Utility and advantages

Attractive and impressive

Diagram simplify the data

Diagrams give more information

Diagrams useful in making comparison

They have universal applicability

Diagrams save time and labor


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Limitations

They give only a vague idea of the

problem

The level of precision of values indicated

by diagrams is very low

They are helpful only when comparisons

are desired

diagrams can represent limited numberof characteristics

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