introduction to statistics

introduction to statictics

1. DATA AND STATISTICS
►Data consists of information coming from observations, counts, measurements, or
responses
►Statistics is the science of collecting, organizing, analyzing, and interpreting data in
order to make decisions.
-Statistics is a set of decision making techniques which aids businessmen in drawing
inferences from the available data

2. ORIGIN OF STATISTICS
►The term statistics has its origin in Latin word Status, Italian word Statists or
German term Statistik. All the three terms mean Political State.
►In ancient periods ,the beginning of statistics was made to meet the administrative
needs of the state.
►In modern times, statistics is not related to the administration of the state alone, but it
has close relation with almost all those activities of our lives which can be expressed
in quantitative terms.

3. MEANING OF STATISTICS
Thetermstatisticshasbeengenerallyusedintwosenses-
(1)Pluralsenseand(2)Singularsense.
►Inpluralsense,thetermstatisticsreferstonumericaldataorstatisticaldata.Statistics,whenused
asapluralnoun,maybedefinedasdataqualitativeaswellasquantitative,thatarecollected,usually
withaviewofhavingstatisticalanalysis.
► Insingularsense,thetermstatisticsreferstoascienceinwhichwedealwiththetechniquesor
methodsforcollecting,classifying,presenting,analyzingandinterpretingthedata.Itmeansitis
‘scienceofcounting’or‘scienceofaverages’.Thesedeviceshelptosimplifythecomplexdataand
makeitpossibleforacommonmantounderstanditwithoutmuchdifficulty.

4. DEFINITION
►“Statistics are numerical statement of facts in any department of enquiry placed in
relation to each other.”
►-A.L.Bowley
►“Statistics may be defined as the science of collection, presentation analysis and
interpretation of numerical data from the logical analysis.”
►-Croxton and Cowden
►“Statistics is the science of learning from data, and of measuring, controlling and
communicating uncertainty
►-American Statistical Association (ASA)

5. Some more definitions

6. The definition of Statistics as given by Horace Secrist
►“Statisticsistheaggregateoffactsaffectedtomarkextentbythemultiplicityof
causes,numericallyexpressed,enumeratedorestimatedaccordingtoa
reasonablestandardofaccuracy,collectedinasystematicmannerforthe
predeterminedpurposeandplacedinrelationtoeachother”.

7. CHARACTERISTICS OF STATISTICS
►StatisticsareAggregateofFacts
►StatisticsareAffectedtoamarkedExtentbyMultiplicity,ofCauses
►StatisticsareNumericallyExpressed
►Statistics are Enumerated or estimated according to Reasonable Standards of
Accuracy
►StatisticsareCollectedinaSystematicManner
►StatisticsforaPre-determinedPurpose
►Comparable

8. DATA COLLECTION
PRIMARY
DATA

9. Types/ Classification of Data
11--1 I
Primary data is the data collected
for the first time through personal
experiences or evidence,
particularly for research. It is also
described as raw data or first-
hand
TYPES
L__/
Secondary data are
secondhand data that is
already collected and recorded
by some researcher for their
purpose and not for the current
research problem.
_ information
^->
PRIMARY
DATA
SECONDAR^^
DATA
Dr. Ankita

10. Difference
Basis Primary Data Secondary Data
Definition Primary data are those which are collected for
the first time.
Secondary data refers to those data which
have already been collected by some other
person.
Originality Primary data is original because these are
collected by the Investigator for the first time.
Secondarydataarenotoriginalbecause
someoneelsehascollectedtheseforhis
ownpurpose.
Nature of dataPrimary data are in the form of raw materials.Secondary data are in the finished form.
Reliability and
Suitability
Dr. Ankita Chaturvedi
Primarydataaremorereliableandsuitablefor
theenquirybecauseitiscollectedfora
particularpurpose.
It is less reliable and less suitable as
someone else has collected the data which
may not perfectly match our purpose.

11. Basis Primary Data Secondary Data
Time and MoneyCollecting primary data is quite expensive both
in time and money terms.
Secondary data requires less time and
money so it is economical.
Precaution and
Editing
No special precaution or editing is required
while using primary data as these have been
collected with a definite purpose.
Both precaution and editing are essential as
secondary data were collected by someone
else for his own purpose.
Data Collection
Source
Primary data can be collected through Surveys,
observations, experiments, questionnaires,
focus groups, interviews, etc.,
secondary data are collected through books,
journals, articles, web pages, blogs, etc.

12. Methods of Collecting Primary Data
1.DirectPersonalInvestigation
2.IndirectOralInvestigation
3.InformationThroughCorrespondents
4.TelephonicInterview
5.MailedQuestionnaire
6.Schedulesfilledbyenumerators

13. Some important terms
Investigator•One who conducts the investigation i.e. statistical enquiry
and seeks information is known as Investigator. •It can be
an individual person or an organization.
Enumerators•Enumerators are the persons who help the Investigators in
the collection of data.
Informant •Informants are the respondents who supply the information
to the investigator or enumerators.

14. MethodsofCollectingPrimary
Data
Direct Personal Investigation•Under this method, the Investigator obtains the first-hand information from
the respondents themselves.
•He personally visits the respondents to collect information (data).
Indirect Oral InvestigationUnder this method, instead of directly approaching the informants, the
investigators interviewed several other persons who are directly or indirectly
in touch with the informants.
Information through
Correspondents
Under this method, local agents or correspondents are appointed and
trained to collect the information from the respondents.
Telephonic Interviews
Under this method, data are collected through an interview over the
telephone.

15. Mailed Questionnaire MethodUnder this method, a questionnaire containing a number of questions
related to the investigation is prepared.
It is then sent to Informants by post along with the instructions to fill. The
Informant after filling up the questionnaire sends it back to the Investigator.
Schedules Filled By
Enumerators Method
Under this method, Enumerator personally visits Informants along with a
schedule, asks questions and note down their response in the schedule in
his own language.

16. Difference between
Questionnaire and Schedule
Basis Questionnaire Schedule
Meaning Questionnaire refers to a technique of data
collection which consist of a series of written
questions along with alternative answers.
Schedule is a formalized set of
questions, statements and spaces for
answers, provided to the enumerators
who ask questions to the respondents
and note down the answers
Filled by Respondents Enumerators
Response Rate Low High
Coverage Large Comparatively small
Cost Economical Expensive

17. Basis Questionnaire Schedule
Respondent's
identity
Notknown Known
Success relies
on
Qualityofthequestionnaire Honesty and competence of the
enumerator.
Usage
Only when the people are literate and cooperative.Used on both literate and illiterate people.
Use of
Abbreviations
Cannotbeused Can be used
Observation
Method
Notapplicable Applicable
Important
features
Dr. Ankita Cha«urvedi
■Simpletounderstand
■Shortquestions
■InterestingandEngaging
No special features required

18. Collection Of Secondary Data
Sources of secondary data can broadly be classified under two Categories:
►1. Published sources
Published sources mean data available in printed form. It includes:
1. Magazines, Journals & Periodicals published by various Government,
Semigovernment and Private organisations. Like, data related to birth, death,
education etc. by the government at various levels; data regarding Prices, Production
etc. published by Economic Times, Financial Express etc.
2. Reports of various Committees or Commissions. Like, report of Pay Commission
Report, Finance Commission Report etc.
3. Reports of International Agencies-Reports are regularly published by agencies
like UNO, WHO, I.M.F. etc.

19. Collection Of Secondary Data
►2.Unpublishedsources
•Allstatisticalmaterialisnotalwayspublished.
•Thiscategoryincluded:
•i.Recordsmaintainedbyvariousgovernmentandprivateoffices.
•ii.Researchstudiesweredonebyscholarstudentsorsomeinstitutions.
•iii.ReportspreparedbyPrivateInvestigationcompaniesetc.
•Suchsourcescanalsobeuseddependingupontheneed.

20. Limitations of Statistics
►Statistics laws are true on average. Statistics are aggregates of facts. So single
observation is not a statistics, it deals with groups and aggregates only.
►Statisticalmethodsarebestapplicableonquantitativedata.
►Statisticalmethodscannotbeappliedtoheterogeneousdata.
►If sufficient care is not exercised in collecting, analyzing and interpretation the data,
statistical results might be misleading.
►Only a person who has an expert knowledge of statistics can handle statistical data
efficiently.
►Statistics relies on estimates and approximations. Thus the statistical inferences
are uncertain or can be misleading.

21. Scrutiny of Data
/XS*
’"X. s'
►Once the data are collected and always they have to be verified for their
homogeneity and consistency. This verification of data is called as scrutiny of data
►No hard and fast rules can be recommended for the scrutiny of data. One must apply
his intelligence, patience and experience while scrutinizing the given information.
.

22. Scrutiny of Data
Scrutinyofprimarydata
►Errors in data may creep in while writing or copying the answer on the part of the enumerator. A keen
observer can easily detect that type of error.
►Thebiasoftheenumeratoralsomaybereflectedbythereturnssubmittedbyhim.
Scrutinyofsecondarydata
►Scrutinizing the secondary data is vital, because the data may be inaccurate, unsuitable or inadequate.
►Data collected by other people cannot be fully depend upon as they may contain many pitfalls and
unless they have been thoroughly verified they should not be used.