data analysis techniques and statistical softwares

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Page 1: data analysis techniques and statistical softwares
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Data Analysis Techniques & Statistical

Software's By

Dr.Ammara KhakwaniIn

Numl Multan Campus

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Estimation Prediction Forecasting

For the purpose of Decision making

about unknown parameters on the basics Estimates

Purpose of Statistical Analysis

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Research report 4 basic components

Problem Design

Data analysis

Summary

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Basis of Statistical analysis

1) Should be carefully planned.

2) Documentation for the usability 3) Computing as an inherent part

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Process data and report the overall trends. 

Process Systematically

Apply Statistical Techniques to describe and

evaluate data.

MEANING OF DATA ANALYSIS

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Not Having the necessary skills to analyze

Not Following acceptable norms for data analysis

Not Choosing the appropriate statistical software

Not Providing honest and accurate analysis

Lack of sense for data presentation

Extended data analysis

ISSUES TO CONSIDER IN DATA ANALYSIS

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Getting data ready for analysis

Coded

Transcribe data from Questionn

aireResponse

No Response

Keyed

softwarefirst

column for

identification

purposes

method

Edited

check 10% of

questionnaires

systematic

sampling

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keyedTo compare

the data in the data file with

the answers of the

participants

Enter this number in the first column of your data file

Write this

number on the

first page of every

questionnaire

Assign a number to

every questionnair

e

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Solution for non-respons

esAssign a

number give a code in

questionnaire

Give a mean value to all

those who have responded

Look at participants pattern of

responses deduce a logical answer

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Summary

Figure Measures

Measures of Central Tendency

Measures of Dispersion

VisualReprsentation

Graphs

Getting a feel for data

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Scale Examples Measures of Central Tendency… for a single Variable

Measures of Dispersion …for a Single variable

Visual Summary …for a single variable

Measure of Relation … between variables

Visual Summary of Relation … between variables

Nominal Social security number gender

Mode ____ Bar chart, pie chart

Contingency table (cross-tab)

Stacked bars, clustered bars

Ordinal Satisfaction rating on a 5-point scale (1=not satisfied at all,5=extremely satisfied

Median Semi-inter Quartile Range

Bar chart pie chart

Contingency table (cross-tab)

Stacked bars, clustered bars

Interval Age15-20Height5-6 feet

Arithmetic Mean

Minimum, maximum, Standard Deviation, Variance,Co-efficient of variation

Histogram, scatter plot,x-and-whisker plot

Correlations Scatters plots

Ratio sales Arithmetic or Geometric mean

Same as above Histogram, Scatter plot,x-and-whisker plot

Correlations Scatters plots

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Relationship between Variables

Significance of Bivariate Relationshi

pInterval Scale

Ordinal Scale

Nominal Scale

Nature Direction

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Ordinal scale

Spearman’sRank correlation

Kendall’sRank correlation

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Software requirements

1. Reliable

2. Well documented

3. User-friendly

4. General

5. Flexible

6. Fast

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Statistical----Package

Computer programme

that specializes in

statistical data analysis.

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1. How Easy Is the Statistical Software to Use?

2. Depth of menued procedures.3. Range and quality of use of procedures offered.4. Modifiability of analytical output. 5. Ease of table output to formatting . 6. Range of Graphical output offered.7. Speed of handling large data sets.8. Ease of results & flexibility of data set manipulation.

Choosing , Few Questions You Should Ask

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Department of use mostly Education researches, Government, Marketing Organizations Telecommunications, Banking, Finance,Insurance, Healthcare, Manufacturing, Retail, Consumer packaged goods,

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1) Knowledge on the theory of the statistical methods, required for planning the analysis and interpret the results

2) Knowledge on the use of the software, required for correctly performing the analysis

3) Knowledge on the computational aspects of the statistical methods, required for developing software (and maybe more)

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Transform raw data into information. Provide a way of drawing inductive

inferences from data. Distinguishing the signal from the

statistical fluctuations present in the data. Statistical procedures are categorized

according to Descriptive, and inferential Statistics .

REASON FOR STATISTICAL ANALYSIS

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For the Social Sciences (SPSS)) Statistical Analysis System (SAS) Econometric Views (EViews) MINITAB STATA R & MATLAB MS-EXCEL

COMMON STATISTICAL SOFTWARE

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MiniTab -- a powerful, full-featured MS Windows , with coverage of industrial quality control analyses.

EasySample -- a tool for statistical sampling.    SAS/STAT http://www.sas.com/ from

descriptive statistics, t-tests, analysis of variance, and predictive modeling to exact methods

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ATLAS.ti http://www.atlasti.com/ ATLAS.ti serves as a powerful utility for qualitative analysis,

 CDC EZ Text    http:/www.cdc.gov/hiv/topics/surveillance/resources/software/ez-text/index.htm

CDC EZ-Text is developed to assist researchers create, manage, and analyze semi-structured qualitative databases.  

NVivohttp://www.qsrinternational.com/ is designed to support a wide range of

research methods,

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Introduction: What is SPSS?

Statistical Package for the Social Science Statistical Product and Service SolutionsPopular statistical packages Complex Data manipulation and analysis with Simple instructions

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SPSS can take data from almost any type of

file and use them to generate tabulated

reports, charts, and plots of distributions

and trends, descriptive statistics, and

conduct complex statistical analyses.

Continued

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Questions in the questionnaire

are mapped into Variables in

SPSS

Translate the Questionnaire

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How is your satisfaction with the customer service of the staff of Bata?

O ExcellentO GoodO BadO Very bad

Missing value

Respons-format :: Closed-Ended

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1 = Excellent 2 = Good3 = Bad4 = Very bad

5 = missing value

Coding the answers

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Please indicate your gender.O FemaleO Male

Codes:1 = Female2 = Male

3 = missing value

Respons-format :: Closed-Ended

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What is your average expenditure in the restaurant on a weekly basis?……… rupees per week .

For how many years have you been registered as a student at B.Z University?……… year(s)

Open-ended with numerical response

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I would like to have the assortment extended with the following products:…………………………………………

Processed by Coding manually afterwards

Open-ended with text response

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Description Order Distance

Nominal Ordinal Scale

Scale characteristics

Levels of Measurement

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Nominal Smoker or non smoker (yes, no);OrdinalIn your opinion, would you say the prices at Chen-one are

O Higher than Cantt. Bazar O About the same as Cantt.O Lower than Cantt.

OrdinalWhat is your age?

O 15–<25O 25–<40O 40–<60O 60–<90

Levels of measurement

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Analyze Frequencies Cross tabs Tables

Graphs

Bar Pie Histogram Line Boxplot

Don’t forget to save◦ Data file

◦ Output file

SPSS Menu’s

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Input data into the computer Organise data Compare data Manage data Summarise data (transform raw data into

information) Generate tables and graphs Facilitate presentation of information and

preparation of analytical reports

RELATION Of DATA ANALYSIS STATISTICAL SOFTWARES

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Opening SPSS Start → All Programs → SPSS Inc→ SPSS 16.0 → SPSS 16.0

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Opening SPSS The default window will have the data editor There are two sheets in the window: 1. Data view 2. Variable view

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The Four Windows: Data editor Output viewer Syntax editor Script window

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Data View The SPSS Data Editor

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Variable View The SPSS Data Editor

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Variable view

◦ Name

◦ Type (Numeric)

◦ Label

◦ Values (= the codes of the answers)

◦ Measure (= Level of Measurement)

The SPSS Data Editor

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The Four Windows: Data Editor Data Editor

Spreadsheet-like system for defining, entering, editing, and displaying data. Extension of the saved file will be “sav.”

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The Four Windows: Output Viewer Output ViewerDisplays output and errors. Extension of the saved file will be “spv.”

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The Four Windows: Syntax editor Syntax Editor

Text editor for syntax composition. Extension of the saved file will be “sps.”

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The Four Windows: Script Window Script Window Provides the opportunity to write full-blown programs, in

a BASIC-like language.

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Data View windowThis sheet is visible when you first open the Data Editor and this sheet contains the data -------------------Click on the tab labeled Variable View

Click

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Variable View window

This sheet contains information about the data set .The first character of the variable name must be alphabetic .Variable names must be unique, and have to be less than 64 characters. Spaces are NOT allowed.

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Variable View window: Type◦ Click on the ‘type’ box. The two basic types of variables that you will use are

numeric and string. This column enables you to specify the type of variable.

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Variable View window: WidthWidth allows you to determine the number of

characters SPSS will allow to be entered for the variable

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Variable View window: Decimals◦ Number of decimals◦ It has to be less than or equal to 16

3.14159265

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Variable View window: Label_You can specify the details of the variable◦ You can write characters with spaces up to 256 characters

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Variable View window: ValuesThis is used and to suggest which numbers represent which

categories when the variable represents a category

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Defining the value labels Click the cell in the values column as shown below For the value, and the label, you can put up to 60 characters. After defining the values click add and then click OK.

Click

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How would you put the following information into SPSS?

Value = 1 represents Male and Value = 2 represents Female

Name Gender HeightJAUNITA 2 5.4SALLY 2 5.3DONNA 2 5.6SABRINA 2 5.7JOHN 1 5.7MARK 1 6ERIC 1 6.4BRUCE 1 5.9

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Practice 1 (Solution Sample)

Click

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Click

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Saving the data To save the data file you created simply click ‘file’ and click ‘save as.’

You can save the file in different forms by clicking “Save as type.”

Click

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Sorting the data Click ‘Data’ and then click Sort Cases

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Sorting the data (cont’d) Double Click ‘Name of the students.’ Then click

ok.

Click

Click

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Practice 2

How would you sort the data by the ‘Height’ of students in descending order?

Answer◦ Click data, sort cases, double click ‘height of

students,’ click ‘descending,’ and finally click ok.

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Transforming data

Click ‘Transform’ and then click ‘Compute Variable…’

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Transforming data (cont’d)

Example: Adding a new variable named ‘lnheight’ which is the natural log of height ◦ Type in lnheight in the ‘Target Variable’ box. Then type in

‘ln(height)’ in the ‘Numeric Expression’ box. Click OK

Click

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Transforming data (cont’d)

A new variable ‘lnheight’ is added to the table

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Practice 3 Create a new variable named “sqrtheight”

which is the square root of height. Answer

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Frequencies◦ This analysis produces frequency tables showing

frequency counts and percentages of the values of individual variables.

Descriptives◦ This analysis shows the maximum, minimum, mean,

and standard deviation of the variables

Linear regression analysis◦ Linear Regression estimates the coefficients of the

linear equation

The basic analysis of SPSS that will be introduced in this class

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Opening the sample data Open ‘Employee data.sav’ from the SPSS Go to “File,” “Open,” and

Click Data

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Opening the sample data Go to Program Files,” “SPSSInc,” “SPSS16,” and “Samples”

folder. Open “Employee Data.sav” file

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Frequencies Click ‘Analyze,’ ‘Descriptive statistics,’ then click ‘Frequencies’

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Frequencies Click gender and put it into the variable box. Click ‘Charts.’ Then click ‘Bar charts’ and click ‘Continue.’

Click Click

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Frequencies Finally Click OK in the Frequencies box.

Click

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Using the Syntax editor Click ‘Analyze,’ ‘Descriptive statistics,’ then click ‘Frequencies.’ Put ‘Gender’ in the Variable(s) box. Then click ‘Charts,’ ‘Bar charts,’ and click ‘Continue.’ Click ‘Paste.’

Click

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Using the Syntax editor Highlight the commands in the Syntax editor

and then click the run icon. You can do the same thing by right clicking the

highlighted area and then by clicking ‘Run Current’

ClickRight Click!

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Do a frequency analysis on the variable “minority”

Create pie charts for it

Do the same analysis using the syntax editor

Practice 4

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Answer

Click

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Descriptives Click ‘Analyze,’ ‘Descriptive statistics,’ then click ‘Descriptives…’ Click ‘Educational level’ and ‘Beginning Salary,’ and put it into

the variable box. Click Options

Click

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Descriptives The options allows you to analyze other descriptive

statistics besides the mean and Std. Click ‘variance’ and ‘kurtosis’ Finally click ‘Continue’

Click

Click

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Descriptives Finally Click OK in the Descriptives box. You will be able to

see the result of the analysis.

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Regression Analysis Click ‘Analyze,’ ‘Regression,’ then click ‘Linear’

from the main menu.

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Regression Analysis For example let’s analyze the model Put ‘Beginning Salary’ as Dependent and ‘Educational Level’ as

Independent.

edusalbegin 10

Click Click

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Regression Analysis Clicking OK gives the result

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Plotting the regression line Click ‘Graphs,’ ‘Legacy Dialogs,’ ‘Interactive,’ and

‘Scatterplot’ from the main menu.

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Plotting the regression line Drag ‘Current Salary’ into the vertical axis box and ‘Beginning

Salary’ in the horizontal axis box. Click ‘Fit’ bar. Make sure the Method is regression in the Fit box.

Then click ‘OK’.

Click Set this to Regression!

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Click on the “fit” tab to make sure the method is regression

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Descriptive Statistics (Summarising Data)

Frequency Distributions◦ Frequency tables◦ Histograms

Central Tendency◦ The mean◦ The median◦ The mode

Variance (spread of data around the mean) The range Standard deviation

Types of Analysis Univariate Analysis

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Types of Analysis

Skewness refers to the degree and direction of asymmetry in a distribution.

No Skew

Positively Skewed Negatively Skewed

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The reliability of a scale indicates how free it is from random error.

Two frequently used indicators of a scale’s reliability are test-retest

reliability (also referred to as ‘temporal stability’) and internal consistency.

Check Reliability

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Be careful

•Do not simply accept and report the format of SPSS computer printout.

•Instead, reformat the data into tables.• •Take some care in reporting tables.

•Provide informative titles.• Be sure to include the Ns