Bernoulli, Binomial & Poisson: What is pi?

In summary, Pi represents the probability of success and is often used in the Bernoulli and Binomial cases. It is also used in the Poisson example, but it can be any positive number and need not be less than 1.
  • #1
zak100
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Homework Statement


Hi,
I have a confusion in knowing Pi in the equations attached. Eq are related to the Topic Discrete Random Variables in the context of Probability lecture
I also can't understand what is P(Y=y|Pi)?

Homework Equations



Eq are attached

The Attempt at a Solution


I can't understand the meaning of Pi. Does it mean probability of success?

Zulfi.
Discrete Random Var Bernoulli Binomial Poisson.jpg
 

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  • #2
zak100 said:

Homework Statement


Hi,
I have a confusion in knowing Pi in the equations attached. Eq are related to the Topic Discrete Random Variables in the context of Probability lecture
I also can't understand what is P(Y=y|Pi)?

Homework Equations



Eq are attached

The Attempt at a Solution


I can't understand the meaning of Pi. Does it mean probability of success?

Zulfi.View attachment 230451
It looks like ##\pi## just represents the parameter of the distribution. So this is not the common definition ##\pi = 3.14##... In the Bernoulli and Binomial cases, ##\pi## is the probability of success, and in the Poisson example, ##\pi## is the average rate of occurrence.
 
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  • #3
Here pi is the "success" probability for the event being counted in each distribution. Bernoulli is basically Binomial with n=1.
 
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  • #4
zak100 said:

Homework Statement


Hi,
I have a confusion in knowing Pi in the equations attached. Eq are related to the Topic Discrete Random Variables in the context of Probability lecture
I also can't understand what is P(Y=y|Pi)?

Homework Equations



Eq are attached

The Attempt at a Solution


I can't understand the meaning of Pi. Does it mean probability of success?

Zulfi.View attachment 230451

Typically, for bernoulli/binomial distributions we have a single-trial "success" probability, often denoted as ##p## but sometimes as ##\pi## or some other symbol. Note that the parameter is in the range from 0 to 1, because it is a probability.

For Poisson distributions we are typically counting something (like the number of successes or failures, or the number of customers arriving at a store, or the number of radioactive decays, etc.) The mean and variance depend on some parameter, and your book is calling that parameter ##\pi##. However, unlike the bernoulli/binomial case, ##\pi## can be any positive number and need not be less than 1.
 
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  • #5
Hi,
Thanks everybody for your replies.
What is meant by P(Y=y|Pi) in the above equations?

Zulfi.
 
  • #6
zak100 said:
Hi,
Thanks everybody for your replies.
What is meant by P(Y=y|Pi) in the above equations?

Zulfi.
It's the probability that a discrete random variable Y (with an assumed distribution) has the value y, given that the parameter of the distribution is ##\pi##.
 
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  • #7
Thanks.

Zulfi.
 

1. What is the Bernoulli distribution?

The Bernoulli distribution is a discrete probability distribution that models the outcomes of a single trial of a binary event, where the outcomes are either success or failure. It is named after Swiss mathematician Jacob Bernoulli.

2. What is the Binomial distribution?

The Binomial distribution is a discrete probability distribution that models the number of successes in a fixed number of independent trials of a binary event. It is derived from the Bernoulli distribution and is named after Swiss mathematician Jacob Bernoulli's father, Johann Bernoulli.

3. What is the Poisson distribution?

The Poisson distribution is a discrete probability distribution that models the number of events that occur in a fixed interval of time or space, given that these events occur at a constant rate and are independent of each other. It is named after French mathematician Siméon Denis Poisson.

4. What is pi and how is it related to these distributions?

Pi (π) is a mathematical constant that represents the ratio of a circle's circumference to its diameter. It is approximately equal to 3.14159. Pi is not directly related to these distributions, but it is often used in their formulas and calculations.

5. How are these distributions used in real-world applications?

The Bernoulli, Binomial, and Poisson distributions are commonly used in statistics and probability to model various real-world phenomena such as coin tosses, disease outbreaks, and customer arrivals. They are also used in fields such as finance, engineering, and biology to make predictions and analyze data.

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