iPhone app ready for download

April 7th, 2011

The Matrix Cookbook is ready for download as app for your iPhone. Check it out here

The Matrix Cookbook as iPhone app

February 20th, 2011

We just signed a contract with Capraro Technologies to make an iPhone app with The Matrix Cookbook. The app will be without ads and cost a small fee. Exactly when it is ready in App Store is not decided, but we will announce it on this website when it is ready for download.

More than 100 citations

March 18th, 2010

According to Google Scholar, The Matrix Cookbook has now been cited more than 100 times by scientific papers. We appreciate the wide spread use and encourage users to cite the cookbook in a way which is consistent with the tradition within their field of research.

For LaTeX users: You can get the bibtex entry here or copy-paste from below:

@MISC\{IMM2008-03274,
author = “K. B. Petersen and M. S. Pedersen”,
title = “The Matrix Cookbook”,
year = “2008″,
month = “oct”,
keywords = “Matrix identity, matrix relations, inverse, matrix derivative”,
publisher = “Technical University of Denmark”,
address = “”,
note = “Version 20081110″,
url = “http://www2.imm.dtu.dk/pubdb/p.php?3274“,
abstract = “Matrix identities, relations and approximations. A desktop reference for quick overview of mathematics of matrices.”
}

Cookbook author at SAS Institute

January 5th, 2010

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.  

Cookbook author looking for new job

November 20th, 2009

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

How to lie with statistics - Trick #2: Claim causality

June 29th, 2009

(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.

How to lie with statistics - Trick #1: Select your sample with bias

June 14th, 2009

(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 you want to show that the political conservatives are getting ahead of the socialists, then just ask people outside the church og financial district instead of the supermarket or subway.
  • If you want to demonstrate that many people are frustrated with delays in the airport - then ask them on a day with heavy rain and many delayed airplanes.
  • If you want to prove that your garden product gives fantastic results, make sure to make the test in a year of good conditions.

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.

How to lie with statistics - a bag of tricks

June 6th, 2009

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. 

 

More than 500,000 downloads

May 28th, 2009

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.

Amazon is stealing - Part 3: Amazon withdraws

May 26th, 2009

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.