ajay – Page 2 – DECISION STATS

Interview Michal Kosinski , Concerto Web Based App using #Rstats

Here is an interview with Michal Kosinski , leader of the team that has created Concerto – a web based application using R. What is Concerto? As per http://www.psychometrics.cam.ac.uk/page/300/concerto-testing-platform.htm

Concerto is a web based, adaptive testing platform for creating and running rich, dynamic tests. It combines the flexibility of HTML presentation with the computing power of the R language, and the safety and performance of the MySQL database. It’s totally free for commercial and academic use, and it’s open source

Ajay- Describe your career in science from high school to this point. What are the various stats platforms you have trained on- and what do you think about their comparative advantages and disadvantages?

Michal- I started with maths, but quickly realized that I prefer social sciences – thus after one year, I switched to a psychology major and obtained my MSc in Social Psychology with a specialization in Consumer Behaviour. At that time I was mostly using SPSS – as it was the only statistical package that was taught to students in my department. Also, it was not too bad for small samples and the rather basic analyses I was performing at that time.

My more recent research performed during my Mphil course in Psychometrics at Cambridge University followed by my current PhD project in social networks and research work at Microsoft Research, requires significantly more powerful tools. Initially, I tried to squeeze as much as possible from SPSS/PASW by mastering the syntax language. SPSS was all I knew, though I reached its limits pretty quickly and was forced to switch to R. It was a pretty dreary experience at the start, switching from an unwieldy but familiar environment into an unwelcoming command line interface, but I’ve quickly realized how empowering and convenient this tool was.

I believe that a course in R should be obligatory for all students that are likely to come close to any data analysis in their careers. It is really empowering – once you got the basics you have the potential to use virtually any method there is, and automate most tasks related to analysing and processing data. It is also free and open-source – so you can use it wherever you work. Finally, it enables you to quickly and seamlessly migrate to other powerful environments such as Matlab, C, or Python.

Ajay- What was the motivation behind building Concerto?

Michal- We deal with a lot of online projects at the Psychometrics Centre – one of them attracted more than 7 million unique participants. We needed a powerful tool that would allow researchers and practitioners to conveniently build and deliver online tests.

Also, our relationships with the website designers and software engineers that worked on developing our tests were rather difficult. We had trouble successfully explaining our needs, each little change was implemented with a delay and at significant cost. Not to mention the difficulties with embedding some more advanced methods (such as adaptive testing) in our tests.

So we created a tool allowing us, psychometricians, to easily develop psychometric tests from scratch an publish them online. And all this without having to hire software developers.

Ajay -Why did you choose R as the background for Concerto? What other languages and platforms did you consider. Apart from Concerto, how else do you utilize R in your center, department and University?

Michal- R was a natural choice as it is open-source, free, and nicely integrates with a server environment. Also, we believe that it is becoming a universal statistical and data processing language in science. We put increasing emphasis on teaching R to our students and we hope that it will replace SPSS/PASW as a default statistical tool for social scientists.

Ajay -What all can Concerto do besides a computer adaptive test?

Michal- We did not plan it initially, but Concerto turned out to be extremely flexible. In a nutshell, it is a web interface to R engine with a built-in MySQL database and easy-to-use developer panel. It can be installed on both Windows and Unix systems and used over the network or locally.

Effectively, it can be used to build any kind of web application that requires a powerful and quickly deployable statistical engine. For instance, I envision an easy to use website (that could look a bit like SPSS) allowing students to analyse their data using a web browser alone (learning the underlying R code simultaneously). Also, the authors of R libraries (or anyone else) could use Concerto to build user-friendly web interfaces to their methods.

Finally, Concerto can be conveniently used to build simple non-adaptive tests and questionnaires. It might seem to be slightly less intuitive at first than popular questionnaire services (such us my favourite Survey Monkey), but has virtually unlimited flexibility when it comes to item format, test flow, feedback options, etc. Also, it’s free.

Ajay- How do you see the cloud computing paradigm growing? Do you think browser based computation is here to stay?

Michal – I believe that cloud infrastructure is the future. Dynamically sharing computational and network resources between online service providers has a great competitive advantage over traditional strategies to deal with network infrastructure. I am sure the security concerns will be resolved soon, finishing the transformation of the network infrastructure as we know it. On the other hand, however, I do not see a reason why client-side (or browser) processing of the information should cease to exist – I rather think that the border between the cloud and personal or local computer will continually dissolve.

About

Michal Kosinski is Director of Operations for The Psychometrics Centre and Leader of the e-Psychometrics Unit. He is also a research advisor to the Online Services and Advertising group at the Microsoft Research Cambridge, and a visiting lecturer at the Department of Mathematics in the University of Namur, Belgium. You can read more about him at http://www.michalkosinski.com/

Stanford Online Courses Delayed Indefinitely

Message from Stanford –

Dear Ajay Ohri,

We’re very excited for the forthcoming launch of Course Name. We’re sorry not to have gotten in touch lately – we’ve been busy generating lots of content, and the system is working really well. Unfortunately, there are still a few administrative i’s to dot and t’s to cross. We’re still hopeful that we’ll go live very soon – we hope not more than a few weeks late.

But since we don’t have a firm timeline right now, we’d rather leave this open and get back to you with a definitive date soon (rather than just promise you a date that’s far enough in the future that we can feel confident about it). We’ll let you know a firm date as soon as we possibly can.

We realize that some of you will have made plans around expecting the course to start in January, and we apologize for any difficulties that this delay may cause.

The good news is that the course is looking great, and we’re thrilled that over X,000 of you have signed up – we can’t wait for the course to start!

See you soon online!

Course Name Course Staff

Some interesting stats (and note the relative numbers)-

67,000 signups for Technology Entrepreneurship

58,000 signups for Cryptography

44,000 signups for Machine Learning

50,000 signups for Design and Analysis of Algorithms

Also see-

http://see.stanford.edu/

and

Check out these other courses:

Entrepreneurship

Computer Science

Topic Models

Some stuff on Topic Models-

http://en.wikipedia.org/wiki/Topic_model

In machine learning and natural language processing, a topic model is a type of statistical model for discovering the abstract “topics” that occur in a collection of documents. An early topic model was probabilistic latent semantic indexing (PLSI), created by Thomas Hofmann in 1999.[1] Latent Dirichlet allocation (LDA), perhaps the most common topic model currently in use, is a generalization of PLSI developed by David Blei, Andrew Ng, and Michael Jordan in 2002, allowing documents to have a mixture of topics.[2] Other topic models are generally extensions on LDA, such as Pachinko allocation, which improves on LDA by modeling correlations between topics in addition to the word correlations which constitute topics. Although topic models were first described and implemented in the context of natural language processing, they have applications in other fields such as bioinformatics.

http://en.wikipedia.org/wiki/Latent_Dirichlet_allocation

In statistics, latent Dirichlet allocation (LDA) is a generative model that allows sets of observations to be explained by unobserved groups that explain why some parts of the data are similar. For example, if observations are words collected into documents, it posits that each document is a mixture of a small number of topics and that each word’s creation is attributable to one of the document’s topics. LDA is an example of a topic model

David M Blei’s page on Topic Models-

http://www.cs.princeton.edu/~blei/topicmodeling.html

a general introduction to topic modeling .
At KDD-2011 a long tutorial about topic modeling. The slides are here .
slides from a talk on dynamic and correlated topic models applied to the journal Science . (Here is a video of the talk.)
a more technical review paper about this field.
David Mimno maintains a bibliography of topic modeling papers and software.

The topic models mailing list is a good forum for discussing topic modeling.

In R,

topicmodels and lda are two R packages for LDA analysis.

Some resources I compiled on Slideshare based on the above- Continue reading “Topic Models”

England rule India- again

If you type the words “business intelligence expert” in Google. you may get the top ranked result as http://goo.gl/pCqUh or Peter James Thomas, a profound name as it can be as it spans three of the most important saints in the church.

The current post for this is very non business -intelligence topic called Wager. http://peterjamesthomas.com/2011/07/20/wager/

It details how Peter, a virtual friend whom I have never met, and who looks suspiciously like Hugh Grant with the hair, and Ajay Ohri (myself) waged a wager on which cricket team would emerge victorious in the ongoing test series . It was a 4 match series, and India needed to win atleast the series or avoid losing it by a difference of 2, to retain their world cricket ranking (in Tests) as number 1.

Sadly at the end of the third test, the Indian cricket team have lost the series, the world number 1 ranking, and some serious respect by 3-0.

What is a Test Match? It is a game of cricket played over 5 days.
Why was Ajay so confident India would win. Because India won the one day world championship this April 2011. The one day series is a one day match of cricket.

There lies the problem. From an analytic point of view, I had been lulled into thinking that past performance was an indicator of future performance, indeed the basis of most analytical assumptions. Quite critically, I managed to overlook the following cricketing points-

1) Cricket performance is different from credit performance. It is the people and their fitness.

India’s strike bowler Zaheer Khan was out due to injury, we did not have any adequate replacement for him. India’s best opener Virender Sehwag was out due to shoulder injury in the first two tests.

Moral – Statistics can be misleading if you do not apply recent knowledge couple with domain expertise (in this case cricket)

2) What goes up must come down. Indeed if a team has performed its best two months back, it is a good sign that cyclicality will ensure performance will go down.

Moral- Do not depend on regression or time series with ignoring cyclical trends.

3) India’s cricket team is aging. England ‘s cricket team is youthful.

I should have gotten this one right. One of the big and understated reasons that the Indian economy is booming -is because we have the youngest population in the world with a median age of 28.

or as http://en.wikipedia.org/wiki/Demographics_of_India

India has more than 50% of its population below the age of 25 and more than 65% hovers below the age of 35. It is expected that, in 2020, the average age of an Indian will be 29 years, compared to 37 for China and 48 for Japan; and, by 2030, India’s dependency ratio should be just over 0.4

India’s population is 1.21 billion people, so potentially a much larger pool of athletes , once we put away our laptops that is.

http://en.wikipedia.org/wiki/Demographics_of_UK

the total population of the United Kingdom was 58,789,194 (I dont have numbers for average age)

Paradoxically India have the oldest cricket team in the world . This calls for detailed investigation and some old timers should give way to new comers after this drubbing.

Moral- Demographics matters. It is the people who vary more than any variable.

4) The Indian cricket team has played much less Test cricket and much more 20:20 and one day matches. 20:20 is a format in which only twenty overs are bowled per side. In Test Matches 90 overs are bowled every day for 5 days.

Stamina is critical in sports.

Moral- Context is important in extrapolating forecasts.

Everything said and done- the English cricket team played hard and fair and deserve to be number ones. I would love to say more on the Indian cricket team, but I now intend to watch Manchester United play soccer.

Note- Presentation

I made this in Nov ,2008- is it still relevant? Maybe.

Data Analyst Interview Questions You Should Practice (brighthub.com)
NBER Data (kauffman.org)
IRS Thoughtfully Discusses Data Dissemination (kauffman.org)
NoSQL: Reconstructing Linked Data and Graph Databases (themindstorms.blogspot.com)
Data creation isn’t the hard part (blogs.forbes.com)
Encryption Questionnaire – Help (edugeek.net)
Five Ways to Improve File Security: Part II of VI (imperva.com)
2008 Kauffman Data Symposium Papers Released (kauffman.org)

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