Introduction to Statistical Packages

Introduction to Statistical Packages

Eugene Tseytlin

Deparment of BioMedical Informatics

University of Pittsburgh

Expectations



NOT to become an expert in any statistical software package



NOT to become an expert statistician



Present an Overview of what solutions are

available with emphasis on free open source

software

About Me

Who

 Senior Software Developer

Where

 Department of BioMedical Informatics, University of Pittsburgh

Areas of Expertise

 Intelligent Tutoring Systems (ITS)

 Natural Language Processing (NLP)

 Digital Imaging: digital microscopy and fMRI

 Machine Learning Technologies

 Java, Matlab, R, RapidMiner, SAS, C/C++, OWL, PHP, Perl

Introduction



Overview of what is available for statistical analysis



Overview of what is popular today and what are the trends for tomorrow



Overview of some individual software packages



Overview of the dataset that we will be using in

next lecture

Available Statistical Packages

Proprietary



Excel



SPSS



MINITAB



SAS

Free Software



LibreOffice Calc



PSPP



EpiInfo



R

What is Used? (Academia)

Figure 7a. Use of data analysis software in academic publications as measured by hits on Google Scholar.

What is Used? (Survey)

What is Used? (Job Market)

Microsoft Excel

Microsoft Excel

COST

 Individual License for

Microsoft Office Professional

$350

 Microsoft Office University Student License: $99

 Volume Discounts available for large organizations and universities

 Free Starter Version

available on some new PCs

PRO

 Nearly ubiquitous and is often pre-installed on new

computers

 User friendly

 Very good for basic

descriptive statistics, charts and plots

CON

 Costs money

 Not sufficient for anything beyound the most basic statistical analysis

Minitab

Minitab

COST

 $1,395.00 per single user license

PRO

 Easy to learn and use

 Often taught in schools in introductory statistics courses

 Widely used in engineering for process improvement

CON

 Costs Money

 Not suitable for very complicated statistical computation and analysis

 Not often used in academic research

SPSS

SPSS

COST

 From $1000 to $12000 per license depending on license type.

CON

 Very expensive

 Not adequate for modeling and cutting edge statistical analysis

PRO

 Easy to learn and use

 More powerful then Minitab

 One of the most widely used statistical packages in

academia and industry

 Has a command line

interface in addition to menu driven user intefrace

 One of the most powerful statistical package that is also easy to use.

SAS

SAS

COST

 Complicated pricing model

 $8,500 first year license fee

CON

 Very very expensive

 Not user friendly

 Steap learning curve

 Relatively poor graphics capabilities

PRO

 Widely accepted as the leader in statistical analysis and

modeling

 Widely used in the industry and academia

 Very flexible and very powerful.

LibreOffice Calc

LibreOffice Calc

LibreOffice is a free and open source office suite,

developed by The Document Foundation. It is descended from OpenOffice.org, from which it was forked in 2010



OpenOffice vs LibreOffice



Star → Sun → Oracle → Apache, Document Foundation



OpenOffice

http://www.openoffice.org/download



LibreOffice

http://www.libreoffice.org/download/

LibreOffice Calc

PRO

 Very similar to Microsoft Excel in functionality and look and feel (earlier

versions)

 User friendly

 Very good for basic

descriptive statistics, charts and plots

 Inter-operable with Microsoft Office

COST

 Free

CON

 Not sufficient for anything beyound the most basic statistical analysis

EpiInfo

EpiInfo

Epi Info is public domain statistical software for epidemiology

developed by Centers for Disease Control and Prevention (CDC) Epi Info has been in existence for over 20 years and is currently

available for Microsoft Windows. The program allows for

electronic survey creation, data entry, and analysis. Within the analysis module, analytic routines include t-tests, ANOVA,

nonparametric statistics, cross tabulations and stratification with estimates of odds ratios, risk ratios, and risk differences, logistic regression (conditional and unconditional), survival analysis

(Kaplan Meier and Cox proportional hazard), and analysis of

complex survey data. The software is in the public domain, free, and can be downloaded from http://www.cdc.gov/epiinfo. Limited support is available

EpiInfo

PRO

 Consists of multiple modules to

accomplish various tasks beyond just statistical analysis.

 ability to rapidly develop a questionnaire

 customize the data entry process

 quickly enter data into that questionnaire

 analyze the data

COST

 Free

CON

 Not a dedicated statistical package

 Not as powerful as

commercial alternative for performing

advanced analysis and modeling

PSPP

PSPP

COST

 Free

PRO

 Aims as a free SPSS

alternative with an interface that closely resembles SPSS

 User friendly

 Good enough for basic statistical analysis

CON

 Lacks many advanced

statistical tests and features that are present in SPSS

 Last version released in 2010

 Not very well known nor widely used

R

R

R provides a wide variety of statistical and graphical techniques, including linear and nonlinear modeling, classical statistical tests, time-series analysis, classification, clustering, and others. R is easily extensible through functions and extensions, and the R community is noted for its active contributions in terms of packages. There are some important differences, but much code written for S runs unaltered. Many of R's standard functions are written in R itself, which makes it easy for users to follow the algorithmic choices made.

R is highly extensible through the use of user-submitted packages for specific functions or specific areas of study. Due to its S heritage, R has stronger object-oriented

programming facilities than most statistical computing languages. Extending R is also eased by its permissive lexical scoping rules.[10]

According to Rexer's Annual Data Miner Survey in 2010, R has become the data mining tool used by more data miners (43%) than any other.[11]

Another strength of R is static graphics, which can produce publication-quality graphs, including mathematical symbols. Dynamic and interactive graphics are available through additional packages.[12]

R

PRO

 Widely used and accepted in industry and academia

 Very powerful and flexible

 Very large user base

 Lots of books and manuals

 Several User Interface Shells available

COST

 Free / Open Source

CON

 Not user friendly

 Requires steep learning curve

Dataset

The Dataset and Story Library

http://lib.stat.cmu.edu/DASL/

DASL (pronounced "dazzle") is an online library of datafiles and stories that illustrate the use of basic statistics methods. We

hope to provide data from a wide variety of topics so that statistics teachers can find real-world examples that will be

interesting to their students. Use DASL's powerful search engine to locate the story or datafile of interest.

Brain Size and Intelligence

Are the size and weight of your brain indicators of your mental capacity? In this study by Willerman et al. (1991) the researchers use Magnetic

Resonance Imaging (MRI) to determine the brain size of the subjects. The researchers take into account gender and body size to draw conclusions about the connection between brain size and intelligence.

http://lib.stat.cmu.edu/DASL/Stories/BrainSizeandIntelligence.html

Methods

 Correlation

 Regression

 Scatterplot

Brain Size and Intelligence

researchers used Magnetic Resonance Imaging (MRI) to determine the brain size of the subjects.

Information about gender and body size (height and weight) are also included. The researchers withheld the weights of two subjects and the height of one subject for reasons of confidentiality.

Number of cases: 40 Variable Names:

Gender: Male or Female

FSIQ: Full Scale IQ scores based on the four Wechsler (1981) subtests VIQ: Verbal IQ scores based on the four Wechsler (1981) subtests

PIQ: Performance IQ scores based on the four Wechsler (1981) subtests Weight: body weight in pounds

Height: height in inches

MRI_Count: total pixel Count from the 18 MRI scans

Conclusion



Statistical analysis is an integral part of any study and publication



While commercial statistical software may cost an arm and a leg, free alternatives do exists.



While some free alternatives don't measure up, others are growing and expending rapidly and

may overtake commercial software in features

and popularity

References

https://sites.google.com/site/r4statistics/popularity http://en.freestatistics.info/

http://lib.stat.cmu.edu/

http://www.comfsm.fm/~dleeling/statistics/notes000.html