ashu s. kedia.pptx

8/16/2019 Ashu S. Kedia.pptx

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Introduction to SPSS

Ashu S. Kedia

Lecturer, Dept. of Civil Engineering,

School of Technology,

PDPU, aisan, !andhinagar


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• SPSS is a software package used for conducting statistical

analysis, manipulating data, and generating table and graphs

that summarize data.

• SPSS performs statistical analysis range from basic descriptive

statistics to advanced inferential statistical, such as regressionmodel, analysis of variance (Anova), factor analysis etc.

• SPSS also contains several tools for manipulating data,

including functions for recording data, macros programming onvisual basic editor, merging data, and aggregating comple

data sets.

Introduction


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A scientist, an engineer, an economist or a physician is interested

in discovering about a phenomenon that he assumes or believes toeist.

!hatever phenomenon that he desires to eplain, he tries to

eplain it by collecting data from the real world and then using

these data he draws conclusions.

"he available data are analyzed with the help of statistical tools

by building statistical models of the phenomenon.

Introduction


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#iologist $ finding the effect of a certain drug on rat metabolism

Psychologist $ discover the process that occur in all human beings

%conomist $ building a model that apply to all salary groups

Population And Sample

Population

Sample

&mpossible $ to study the entire unit

Practical $ to study a handful of observations, draws conclusions on

entire unit.


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Population refers to all possible observations that can be made on a specific

characteristic.

'or a biologist, the term population could mean all the rats now living and all rats

yet to be born or it could mean all rats of a certain species now living in a specific

area.

#iologist cannot collect data from every rat and the psychologist cannot collect data

from every human being. "herefore, he collects data from a small subset of the

population known as sample and use these data to infer on the population as a

whole.

&f engineers want to build a dam, they cannot make a full*size model of the dam theywant to build+ instead they build a small scale model and tests this model under

various conditions. "hese engineers infer how the full*sized dam will respond from

the results of the small*scale model.

"herefore, in real life situations we never have access to the entire population, so wecollect smaller samples and use the characteristics of the sample to infer the

characteristics of the population.

"he larger the sample, the more likely it is to represent the whole population. &t is

essential that a sample should be representative of the population from which it isdrawn


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Observations and Variables

&n statistics, we observe or measure characteristics called variables. "he study

subects are called observational units.

'or eample, if the investigator is interested in studying the household income

and household size among - families, the //& and //S are the variables, the

//& and //S values are the observations and the families are the observational

units.

&f the investigator records the family0s vehicle ownership, number of working

members, number of students in addition to //& and //S, then he has a data setof - families with observations recorded on each of five variables (//&, //S,

12, 3!4, 3%4) for each family or observation unit.


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Variables and Scales

5uantitative or 4easurement 1ariable on &nterval Scale

"here are numerous characteristics found in the world which can be measured in

some fashion. Some characteristics like height, weight, temperature, salary etc. are

6uantitative variables.

Since these variables are capable of eact measurements and assume, at least

theoretically, infinite number of values between any two fied points. "he data

collected on such measurements are called continuous data and we use interval scale

for these data. 'or eample, height of individuals can be fied on some interval like 7*

8, 8*9, 9*: feet.

2n the other hand, number of children in a family can be counted as ,-,7,8,.. and the

number of families having these many children can be counted and given. /ere the

number of children is -,7,8,.. and not any intermediate value as -.: or 7.8. Such a

variable is called discrete variable.


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Variables and Scales

5ualitative 1ariable on 3ominal Scale

• /ere the units are assigned to specific categories in accordance with certain

attributes. 'or eample, gender is measured on a nominal scale, namely male and

female.

• 5uantitative variable is an attribute and is descriptive in nature. 'or eample,

colour of a person like fair, whitish and dark.

;anked 1ariable on 2rdinal Scale

Some characteristics can neither be measured nor counted, but can be either ordered

or ranked according to their magnitude. Such variables are called ranked variables.

/ere the units are assigned an order or rank. 'or eample, income of the people can

be categorized as low income, middle income and high income. "he only re6uirement

is that the order is maintained throughout the study.


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SPSS looks a lot like a typical spreadsheet application. Spreadsheets, on the other

hand, are capable of a lot of things that SPSS is good at, like generating graphs and

statistics on a data set.

• Spreadsheets are designed to be very fleible and broadly applicable to manydifferent tasks, while SPSS was designed specifically for statistical processing

of large amounts of data at an enterprise level.

• 'or eample, unlike a spreadsheet, SPSS has the concepts of case and

variable built in. "he rows in SPSS always represent cases, for eample

survey responses or eperimental subects, and the columns always representvariables observed from those cases, like the specific values given by the survey

respondents.

•


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Strengths

• 1ery robust statistical software

• 4any comple statistical tests available

• >ood stats coach help with interpreting results

• %asily and 6uickly displays data tables

•


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4any commercial products available SAS, Statistica, 4initab,

and others

Excel

!idely available (part of 4S 2ffice Suite) 3ot a statistical

software $ spreadsheet

'inance, math, and statistics applications

SPSS

;obust software for sophisticated statistical applications


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Applications of SPSS

"ransportation 4odelling

4edical Sciences

4anagement

Social Sciences

Types of Variables

=iscrete 1ariables


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SPSS ATA !ILE


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SPSS ATA !ILE

• 2pening a =ata file in SPSS

•


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SPSS ata Editor

"wo spreadsheets like an array

=ata %ditor 1ariable 1iew B =ata 1iew

=ata 1iew $ new data is entered

1ariable 1iew $ contains the names and details of the variables of

the data.

Status #ar $ SPSS Processor is ready=ata is typed directly in the SPSS data file created already in the

=ata %ditor

=ata can also be imported from the %cel and Statistica

SPSS $ %ach row represents only one case and each column

represents a variable or a character of the case measured.


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SPSS ata Editor





the data.


=ata %ditor





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SPSS Variable Vie"





the data.


=ata %ditor





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Variable Vie"# etails

3ameC string character (normally letters and spaces, and sometimes

digits). &t appears at the head of a column in =ata 1iew but not in the

output. &t is a shortened view that appears only within the data view. &tshould be a continuous se6uence with no space. "hough D9 letters can

be entered it is desirable to keep it short.

"ypeC &t accepts eight different types of variables. "wo important onesare the numeric, i.e., numeral with decimal point

and string, i.e., names of participants, cities or any non*numeric

characters.

!idthC &t is the width of the variable. =efault setting for the width of

the variable is E. %dit $ options $ =ata.

=ecimalsC &t is the number of decimals that will be displayed in the

=ata 1iew. =efault is 7.


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Variable Vie"# etails

FabelC is a meaningful phrase with spaces in between words. &t

describes the variable and also appears in the output. &t is important to

assign meaningful labels for the variables.

1aluesC "his column is meant for grouping variables. &t gives the keys

to the meanings of code numbers. "he value dialog bo is opened by

clicking the grey area. "he value and value labels are given in thevalue dialog bo.

4issing 1alueC &t specifies the missing values in a data set.

ashu s. kedia.pptx

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