Normal and power law distributions

In summary, the conversation discusses the relationship between independent and dependent random events and the resulting distribution. The hypothesis is that as the values of i and j increase, the sums of independent events approximate a normal distribution and the products of dependent events approximate a power-law distribution. A spreadsheet was used to create a table of random numbers, calculate the sums or products, and graph the frequency of each "bin".
  • #1
erszega
36
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Is it correct to say that independent random events (additively) lead to a normal distribution, and dependent random events (multiplicatively) lead to a power law distribution?

The following might be trivial, but it was quite interesting to find for me, someone with a very limited knowledge of mathematics or statistics:

Take a matrix of random numbers r(i,j), where 0 < r(i,j) < 1.

Let S(i) = int( ( r(i,1) + r(i,2) +...+ r(i,j) )*n ), with S(i) >= S(i-1) if i >= i-1, that is, S is a sorted list of the integer parts of the sums of random numbers multiplied by an integer.

Let P(i) = int( ( r(i,1) * r(i,2) * ... * r(i,j) )*n ), with P(i) >= P(i-1) if i >= i-1, that is P is a sorted list of the integer parts of the products of random numbers multiplied by an integer.

Hypothesis (based simply on observation of graphs of S(i) and P(i)):

the higher the values of i and j, the more S(i) approximates normal distribution, and P(i) approximates a power-law distribution.

Is this right?
 
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  • #2
Apologies, I meant the frequency of each S(i) or P(i).
It may be better to describe what I did in the following way:
I used a spreadsheet, and created a table, consisting of, say, 10,000 rows and 5 columns, of random numbers (using the spreadsheet's random number function). Then I added (or multiplied) the random numbers in each row. I multiplied the sums (or products) by, say, 100, and took the integer parts (to create "bins"). Then I sorted the "bins", calculated the frequency (number of occurencies in the list) of each "bin", and then put a graph on the frequency list. I hope this makes sense.
 
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1. What is a normal distribution?

A normal distribution, also known as a Gaussian distribution, is a type of probability distribution that is symmetrical and bell-shaped. It is commonly used to model real-world phenomena such as human height, test scores, and stock prices.

2. How is a normal distribution different from a power law distribution?

A normal distribution is characterized by a single peak and gradually decreasing tails, while a power law distribution has a long tail that does not decrease as quickly. Additionally, a normal distribution is symmetrical while a power law distribution is often skewed.

3. What is the significance of normal and power law distributions in science?

Normal and power law distributions are important in science because they can be used to model a wide range of natural phenomena and are often found in real-world data. Understanding these distributions can help scientists make predictions and draw conclusions about their data.

4. How are normal and power law distributions related to the central limit theorem?

The central limit theorem states that when independent random variables are added together, their sum tends towards a normal distribution regardless of the distribution of the individual variables. This makes the normal distribution a fundamental concept in statistics, and the power law distribution can be seen as a generalization of the normal distribution.

5. What are some common applications of normal and power law distributions?

Normal distributions are commonly used in fields such as statistics, physics, and economics to model natural phenomena. Power law distributions are often found in social sciences, biology, and computer science to describe phenomena such as income distribution, city sizes, and internet usage patterns.

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