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Transcript of data analysis techniques and statistical softwares
Data Analysis Techniques & Statistical
Software's By
Dr.Ammara KhakwaniIn
Numl Multan Campus
Estimation Prediction Forecasting
For the purpose of Decision making
about unknown parameters on the basics Estimates
Purpose of Statistical Analysis
Research report 4 basic components
Problem Design
Data analysis
Summary
Basis of Statistical analysis
1) Should be carefully planned.
2) Documentation for the usability 3) Computing as an inherent part
Process data and report the overall trends.
Process Systematically
Apply Statistical Techniques to describe and
evaluate data.
MEANING OF DATA ANALYSIS
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
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
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
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
Summary
Figure Measures
Measures of Central Tendency
Measures of Dispersion
VisualReprsentation
Graphs
Getting a feel for data
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
Relationship between Variables
Significance of Bivariate Relationshi
pInterval Scale
Ordinal Scale
Nominal Scale
Nature Direction
Ordinal scale
Spearman’sRank correlation
Kendall’sRank correlation
Software requirements
1. Reliable
2. Well documented
3. User-friendly
4. General
5. Flexible
6. Fast
Statistical----Package
Computer programme
that specializes in
statistical data analysis.
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
Department of use mostly Education researches, Government, Marketing Organizations Telecommunications, Banking, Finance,Insurance, Healthcare, Manufacturing, Retail, Consumer packaged goods,
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)
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
For the Social Sciences (SPSS)) Statistical Analysis System (SAS) Econometric Views (EViews) MINITAB STATA R & MATLAB MS-EXCEL
COMMON STATISTICAL SOFTWARE
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
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,
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
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
Questions in the questionnaire
are mapped into Variables in
SPSS
Translate the Questionnaire
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
1 = Excellent 2 = Good3 = Bad4 = Very bad
5 = missing value
Coding the answers
Please indicate your gender.O FemaleO Male
Codes:1 = Female2 = Male
3 = missing value
Respons-format :: Closed-Ended
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
I would like to have the assortment extended with the following products:…………………………………………
Processed by Coding manually afterwards
Open-ended with text response
Description Order Distance
Nominal Ordinal Scale
Scale characteristics
Levels of Measurement
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
Analyze Frequencies Cross tabs Tables
Graphs
Bar Pie Histogram Line Boxplot
Don’t forget to save◦ Data file
◦ Output file
SPSS Menu’s
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
Opening SPSS Start → All Programs → SPSS Inc→ SPSS 16.0 → SPSS 16.0
Opening SPSS The default window will have the data editor There are two sheets in the window: 1. Data view 2. Variable view
The Four Windows: Data editor Output viewer Syntax editor Script window
Data View The SPSS Data Editor
Variable View The SPSS Data Editor
Variable view
◦ Name
◦ Type (Numeric)
◦ Label
◦ Values (= the codes of the answers)
◦ Measure (= Level of Measurement)
The SPSS Data Editor
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.”
The Four Windows: Output Viewer Output ViewerDisplays output and errors. Extension of the saved file will be “spv.”
The Four Windows: Syntax editor Syntax Editor
Text editor for syntax composition. Extension of the saved file will be “sps.”
The Four Windows: Script Window Script Window Provides the opportunity to write full-blown programs, in
a BASIC-like language.
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
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.
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.
Variable View window: WidthWidth allows you to determine the number of
characters SPSS will allow to be entered for the variable
Variable View window: Decimals◦ Number of decimals◦ It has to be less than or equal to 16
3.14159265
Variable View window: Label_You can specify the details of the variable◦ You can write characters with spaces up to 256 characters
Variable View window: ValuesThis is used and to suggest which numbers represent which
categories when the variable represents a category
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
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
Practice 1 (Solution Sample)
Click
Click
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
Sorting the data Click ‘Data’ and then click Sort Cases
Sorting the data (cont’d) Double Click ‘Name of the students.’ Then click
ok.
Click
Click
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.
Transforming data
Click ‘Transform’ and then click ‘Compute Variable…’
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
Transforming data (cont’d)
A new variable ‘lnheight’ is added to the table
Practice 3 Create a new variable named “sqrtheight”
which is the square root of height. Answer
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
Opening the sample data Open ‘Employee data.sav’ from the SPSS Go to “File,” “Open,” and
Click Data
Opening the sample data Go to Program Files,” “SPSSInc,” “SPSS16,” and “Samples”
folder. Open “Employee Data.sav” file
Frequencies Click ‘Analyze,’ ‘Descriptive statistics,’ then click ‘Frequencies’
Frequencies Click gender and put it into the variable box. Click ‘Charts.’ Then click ‘Bar charts’ and click ‘Continue.’
Click Click
Frequencies Finally Click OK in the Frequencies box.
Click
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
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!
Do a frequency analysis on the variable “minority”
Create pie charts for it
Do the same analysis using the syntax editor
Practice 4
Answer
Click
Descriptives Click ‘Analyze,’ ‘Descriptive statistics,’ then click ‘Descriptives…’ Click ‘Educational level’ and ‘Beginning Salary,’ and put it into
the variable box. Click Options
Click
Descriptives The options allows you to analyze other descriptive
statistics besides the mean and Std. Click ‘variance’ and ‘kurtosis’ Finally click ‘Continue’
Click
Click
Descriptives Finally Click OK in the Descriptives box. You will be able to
see the result of the analysis.
Regression Analysis Click ‘Analyze,’ ‘Regression,’ then click ‘Linear’
from the main menu.
Regression Analysis For example let’s analyze the model Put ‘Beginning Salary’ as Dependent and ‘Educational Level’ as
Independent.
edusalbegin 10
Click Click
Regression Analysis Clicking OK gives the result
Plotting the regression line Click ‘Graphs,’ ‘Legacy Dialogs,’ ‘Interactive,’ and
‘Scatterplot’ from the main menu.
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!
Click on the “fit” tab to make sure the method is regression
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
Types of Analysis
Skewness refers to the degree and direction of asymmetry in a distribution.
No Skew
Positively Skewed Negatively Skewed
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
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