Lx=d: SundayResearch

My friends translated 'Peter the cat' by Murakami, Haruki to English and German to learn German. As far as I know, this article is only available in Japanese. This seems useful for learning Japanese/English/German, I post it here. If there is any problem, please let me know. 1 2 3 4 5 6 7 8

Let's visualise how a someone is special in the Figure1. In Figure 1, the area filled by blue region is x <= +- 1σ people. Again, in the Gauss distribution, the center is the average. People are apart from the average, then number of such special people rapidly decreases. The red area of Figure 2 shows the people who are not in the area of x <= +-1σ. Figure 1: Inside of sigma 1 region. Figure 2: Outside of 1sigma region. Gauss choose the parameter to make the total area of the curve to one. So, we can just compute any area of this graph, then we know the degree of speciality from the area. If you are in the area 0.7, you are in the range of 70% people. Great job, Gauss! I cannot compute this area by hand, therefore I asked a clever program. That answered me that the blue area of Figure 1 is 0.6827. This means, 68% people is in 1σ (more accurately +-1σ). By the way, some statistics defines the ``normal person'' living in between +-2σ (95.4%) or +-3σ (99.7

Average and variance of salary/month The story started with variance, I should have told you also another important concept --- average. If you heard a company A's average salary for a month is 25,500 Euro, you might interested in to join the company. But, this company has only two people, a president and an employee. The president gets 50,000 Euro/month, and the employee gets 1,000 Euro/month. Now you see how average can deceive you. A company B is also two people company, but the president gets 30,000 Euro/month and the employee gets 21,000 Euro/month. CompanyA salary of president 50,000 Euro/month salary of employee 1,000 Euro/month Average of salary 25,500 Euro/month CompanyB salary of president 30,000 Euro/month salary of employee 21,000 Euro/month Average of salary 25,500 Euro/month The averages are the same! If I can choose one of them as an employee, I will choose B. But, if they can provide only average, I can not see the difference. That's bad!

Originally, I would like to continue to talk about the determinant, but, for a while, I would like to write about sigma story. And I will come back to the determinant again. Starting with a question Have you ever met a 6σ person? What is 6σ? When I lived in Saarbruecken, I saw a huge woman working in the Karstadt. I believe it's not true, but a rumor said, she stacked in a register seat when she was working. But I cannot say that is not a true... It is hard to find such a person in Japan. The distribution of Japanese's height or weight seems narrower than Germany's one. I feel the distribution of USA people is wider than those two countries. It means, large people are larger than others in USA, I think. 'Average' is an important concept in statistics, and this 'distribution' is the second important concept in statistics. The distribution, i.e., how the people have different weight, or how the people are close to their average weight. In mathemati