Starting January 1, Kaare Brandt Petersen is now working in SAS Institute (But thank you for the kind comments and tips on other positions people has emailed).
SAS Institute is the vendor of the statistics- and information management software SAS, started back in 1976 in University of North Carolina. Kaare Brandt Petersen will be working in the Copenhagen office as Business Advisor, advocating the use of SAS and data analysis.
Kaare Brandt Petersen, one of the authors of The Matrix Cookbook, is currently looking for his next job (No, updating the cookbook is not a full time job yet). If you have some good ideas or offers - drop him an email at
kaarebrandt (at) gmail (dot) com
You can look at his resume at his LinkedIn profile or at this old school website
(If you go “Lying with statistics is unethical - what is this?” then read the intro)
A comonly used way to misuse statistics, is to claim causality between two entities of which a relation has been demonstrated. For example
a) If people eating apples have longer live expectancy, then present the results as if it was because of the apples. The truth may be that people eating apples are more likely to do more exercise, but that concern won’t sell your apples, right?
b) If people wearing a tie have higher average income, then you can claim it was because of the excelent silk ties you are selling. The truth probably is that people wearing a tie have made other carrier choices from early on in their life, but never mind.
In case you want to counter a causality claim, remember that NO data, NO statistics and NO mathematics can formally imply causality. Causality is the result of scientific theories or everyday comon sense. Thus, if the reason for one entity causing another is not clear, it is probabily just a wild guess of the authors.
(If you go “Lying with statistics is unethical - what is this?” then read the intro)
A very simple trick to fool the crowd is to conduct your survey under “the right circumstances”, e.g., select carefully when or who to ask in order to get the answer you are looking for. For example:
If your want to counter the results of a survey, investigate carefully how the data was collected and how this affects the outcome. Everybody making a survey has a preferred outcome, and if you have identified the preferrences, you can start think of how this most likely have influenced the sampling - conciously or not.
It is not just a phrase - there is actually a book with the title “How to lie with statistics”. It is by Darrell Huff, was first published in 1954 and according to Wikipedia the best selling statistics book in the second half of the 20th century. The examples are from back then, but the points maken are amazingly relevant still today. Huff shows some of the most frequent flawed and fraudulent statistics and it is worth reading for the basic knowledge - as a manual on how NOT to get fooled by the tricks of sales people, lobbyists, evil statisticians or undereducated civil servants.
As a celebration, and because its pretty good fun, I’ll run a series of postings on how to lie with statistics - the tricks of the trade. Most of them will be from the book by Huff, but some of my own experience.
The Matrix Cookbook has passed the magic boundary of half a million downloads since the first release in August 2004. And the cookbook is still the most downloaded document at Department of Informatics and Mathematical Modelling, Technical University of Denmark. Yay.
This is a continued story - read also Part 1 and Part 2. I have received the following mail from Amazon:
Dear Mr. Petersen:
Thank you for your message. Without any admission of wrongdoing, please be advised that we are in the process of removing ”The Matrix Cookbook (Kindle Edition)” ASIN: B0027P9C2S from Amazon.com. It typically takes 2-3 days for a listing to disappear once it has been removed from our catalog. We trust this will bring this matter to a close.
This letter is written without prejudice to any rights, remedies or defenses to which Amazon.com and its affiliates may be entitled, all of which are expressly reserved.
Thank you - what a relief.
This is continued story starting here. Ok, so they didn’t respond to the first email sent via a webform to Amazon Kindle. Today I sent the following mail to copyright@amazon.com
Dear Sirs/Madams
I have found out that the document “The Matrix Cookbook” is available from Amazon Kindle
http://www.amazon.com/The-Matrix-Cookbook-ebook/dp/B0027P9C2S
I am co-author of the document, and have no idea how or why it has ended on Amazon. The copyright holder is Technical University of Denmark and they have not authorized this, so I will strongly urge you to remove it from your services immediately.
On the kindle website, the document have so-called editors named “TFTPG” which stands for The Flying Tigers Printing Group (http://www.tftpg.com). “The Matrix Cookbook” has nothing to do with this organization and I don’t know why they are related on Amazon.
I would appreciate a swift respons to this email. Thanks.
Best regards, Kaare
Lets see if that helps …
This morning, I found out that The Matrix Cookbook is being sold at Amazon (Kindle version). How often does that happen - that Amazon find something on the internet and starts making money on it, without even contacting the authors, publisher, copyright holders, or someone otherwise related to the material?
So I wrote them an email instructing them to remove it immediately - lets see if they have the curtesey to respond to that.
Stephen Wolfram, the guy behind the software Mathematica, has launched something called Wolfram Alpha. Wolfram Alpha is a kind of search engine with a very ambitious goal; in their own words: “Wolfram|Alpha’s long-term goal is to make all systematic knowledge immediately computable and accessible to everyone. We aim to collect and curate all objective data; implement every known model, method, andalgorithm; and make it possible to compute whatever can be computed about anything.” Ambitious indeed.
Typing in “Matrix”, the result is a help page on matrix computations, i.e., one can compute the trace, determinant, eigenvalue, etc about a specific matrix typed in, in a Mathematica-like syntax. The output for a specific matrix is a colorplot of the matrix along with the computed trace, determinant, eigenvalues, eigenvectors and inverse.
Entering positive definite, Hadamard matrix or covariance matrix, Wolfram Alpha doesn’t find anything, which means that Wolfram Alpha is either in a beta stage or is not very focussed on matrix matters.
In contrast to Google, Wolfram Alpha can compute results and present them with graphs which is a major step forward and places Wolfram Alpha as more of a knowledge gateway than a search engine. But there seem to be quite a gap from the ambitions and the present level of completeness.