ITS 03 Basics

8/3/2019 ITS 03 Basics

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Jahangirnagar University Islam, M.T. http://sites.google.com/site/kjatbd/

Statistics: What and Why

Md. Tarikul IslamJahangirnagar University, Bangladesh


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The Course: Topics

No Topics

01 Basics of statistics and recap!

02 Collection of data

03 Presentation of data

04 Measures of central tendency

05 Measures of variation

06 Skewness, moments, and kurtosis

07 Correlation analysis

08 Regression analysis

09 Forecasting and time series analysis

10 Probability

11 Sampling


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Todays Topics

qTodays topics Major questions to explore

o What is statistics?o Why to study statistics?o Ethics in statisticso Statistics: science or arts?


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Statistics: ?

qStatistics Statistics

o What is statistics?

Any idea?How do we use the word frequently?


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Statistics: A numerical presentation

qNumerical Presentation These all are data

o Sales are assumed to increase by 10%o Population grows at a rate of 3%o

Production and sales changes by various figures

By statistics most average people perceives this But as data are generally dry, we present them with

graphs, figures, and diagrams


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A numerical presentation: Dry data


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A numerical presentation: Graphs/Figures


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Statistics: A body of methods

qA body of methodso Like all other subjects statistics also has formulae, theories, and

symbols

o Therefore this is also a body of methods to obtain and analyzedata in order to base decisions on them

o So statistics is either quantitate data or the methods of dealingwith quantitative data


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Statistics: A tool in processing

qA tool in processingo Statistics is not studies for its own sake, rather its widely

employed as a highly valuable tool in the analysis of problems

in natural, physical, and social science

o Whatever the scenario, we deal with data in statisticsBut what kind of data?Also what is data?What are the different types of data?What are the characteristics of good data


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Data: Defining

qDatao The term data refers to qualitative or quantitative attributes of

a variable or set of variables

o They are typically the results of measurements and can be thebasis of graphs, images, or observations of a set of variables

o Raw elements that to process to get information followed byknowledge

o A collection of data is called data set and any single data iscalled data point


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Data: Types

qTypes Primary

oCollected for the firsttime

Questionnaire Secondary

o Data that alreadyexists

www.bbs.gov.bd

qTypes Quantitative

oExpressed numerically

He is 5.5 feet tall

Qualitativeo N o t e x p r e s s e d

numerically

He is tallo It can be continuous or

discrete


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Data: Types

qTypes Nominal data

o A set of data is said to be nominal if the values / observationsbelonging to it can be assigned a code in the form of a

number where the numbers are simply labels

o Here observations can only be classified or counted and thereis no particular order

o In a class there are boys and girls. We can say there are boys(1) and girls (2) or we can say 15 girls and 10 boys

Company TotalSubscribers Percent

GP 70 70%

Robi 15 15%

B.Link 15 15%

Total 100 100%


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Data: Types

qTypes Ordinal data

o A set of data is said to be ordinal if the values / observationsbelonging to it can be ranked (put in order) or have a ratingscale attached.

o They are arranged in an order which reveals the position ofone in respect of others

o You can count and order these dataRa6ng Noofstudents

A+ 20

A 12

D 5


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Data: Types

qData Types Interval data

o An interval scale is a scale of measurement where thedistance between any two adjacent units of measurement (or'intervals') is the same but the zero point is arbitrary

oDifference between 1981 and 1982 is 365 days. Same for 1983and 1984. Here zero is 01 AD; time did not begin then

o 0 degree Fahrenheit means -18 degree Celsiuso This data can be added or subtracted meaningfully but cant

be multiplied or divided meaningfully


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Data: Types

qTypes of data Ration data

o In a ratio scale, numbers can be compared as multiples ofone another. Thus one person can be twice as tall as anotherperson

o Important also, the number zero has meaning, therefore notonly difference but also ratio has the meaning

o Difference in between 1&2 and 3&4 is same, but 4 is twice of 2 Quantitative data can be continuous or discrete But dont mingle with the types of numbers

o How many types of numbers are there?


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Numbers: Types

qTypeso Ordinal

Related to the sequence of one in relation to others like1st, 2nd, 3rd etc.

o CardinalBasic or primary values like 1,2,3, 12, 120 etc.


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Data: Characteristics

qCharacteristicso Relevanceo Reliabilityo Timeliness

o RememberGIGO = Garbage In Garbage Out


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Statistics: Definition

qDefinition However

o Statistics is the aggregation of facts affected to a markedextent by multiplicity of causes, numerically expressed,enumerated or estimated according to reasonable standards

of accuracy, collected in a systematic manner for a pre-determined purpose and placed in relation to each other


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Statistics: Characteristics

qCharacteristics Characteristics

o Aggregation of facts through creating relationshipso There are lots of factors in statistics that are co-relatedo Statistical expressions are numericalo Statistics estimates thorough maintaining reasonable

accuracy

o Statistics includes a systematic mannero There are pre-determined purpose for using statisticso Comparison based on same characteristics of datao All statistics are numerical statements but all numericalstatements are not necessarily statistics


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Statistics: Types

qTypes Descriptive statistics

o Methods of organizing, summarizing, and presenting data inan informative way

o Simply describing dataExample includes mean, range etc.

Inferential statisticso The methods used to find out something about a population,

based on a sample

o Also called statistical inference or inductive statisticso Making decision based on sample data

Population is the collection of all possible individuals,objects, or measurements of interest

Sample is a portion or part of the population of interest


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Statistical method: 1/3

qStatistical method Statistical method

o A method of science having five stages toCollect data

Organize dataPresent dataAnalyze data andInterpret data


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qStatistical method Data collection

o GIGOo Data characteristics

Data organizationo Data editingo Data classificationo Data tabulation


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qStatistical method Data presentation

o Presentation in a systematic manner

Data analysiso Use of different tools like models, formulae etc

Result interpretationo Your mastery in interpretation makes you different than others

always!!


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Statistics: Science or Art?

qScience or Art? The debate

o What is science?o What is arts?o Statistics is not a body of substantive knowledge but a body of

methods for obtaining knowledge


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Statistics: Science?

qScience?o Science is like a lighthouse that gives lights to the ships to find

out their own way but does not indicate the direction in which

one should go

o Its a body of knowledge that studies the cause and effectrelationship and attempts to make generalizations ofprinciples and laws

o Statistics is also a body of knowledge but not with theaccuracy that natural science has

o So its a science but one kind of specialized science


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Statistics: Art?

qArt?o Art is all about the ways and means to achieve a given

objective

o With this definition statistics is also an art as it includes variedapplications to obtain facts and derive results to reach at aparticular point


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Functions of statistics

qFunctions of statistics Functions

o Presents facts in definite formo Simplifies the mass figureo Facilitates comparisono Helps in formulation and testing of hypothesiso Helps in predictiono Helps in formulation of suitable policies


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Scope of statistics

qScope of statistics Scopes

o With the stateo In business managemento Research and statistics

o In reality its a multidimensional field


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Limitations of statistics

qLimitations of statistics Limitations

o Does not deal with isolated datao Deals with quantitative data onlyo Results are true only on an averageo Its just a meanso It can be misused


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Ethics in statistics

qEthics in statistics Ethics

o There are basically three lies-lies, damn lies, and statistics!!!


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qThank You!

qAny Question?!

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ITS 03 Basics