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Genuine help needed

stuwii

By stuwii
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stuwii Newbie

stuwii

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Posted

Need some resources linked to s2 for a2 maths. The poisson as an approximation to the binomial.

 

This page need be used only for those binomial situations in which n is very large and p is very small. For example: The null hypothesis holds that a certain genetic characteristic will express itself in p=.001 of the population. In a sample of n=3000 subjects, k=7 are observed to display the characteristic, whereas only np=3 are expected. On the null hypothesis, how likely is it that a rate this great or greater could occur by mere chance? Your computer would not be able to perform the factorial and exponential operations required for direct calculation (Exact Binomial Probability Calculator), and np<5 would preclude use the normal approximation (Binomial z-Ratio Calculator).

 

In cases of this sort, the appropriate binomial probabilities can be approximated by way of the Poisson probability function

 

TP(k out of n) = (e—np)(npk)

 

k!

where:

e = the base of the natural logarithms;

n = the number of opportunities for event x to occur;

k = the number of times that event x occurs or is stipulated to occur; and

p = the probability that event x will occur on any particular occasion;

 

Application of the Poisson function using these particular values of n, k, and p, will give the probability of getting exactly 7 instances in 3000 subjects. Applying it to all values of k equal to or greater than 7 will yield the probability of getting 7 or more instances in 3000 subjects, while applying it to all values of k equal to or smaller than 7 will give the probability of getting 7 or fewer instances in 3000 subjects. Note, however, that these results are only approximations of the true binomial probabilities, valid only in the degree that the binomial variance is a close approximation of the binomial mean.

 

To perform calculations of this type, enter the appropriate values for n, k, and p (the value of q=1—p will be calculated and entered automatically). Then click the 'Calculate' button. To enter a new set of values for n, k, and p, click the 'Reset' button. The value entered for p can be either a decimal fraction such as .001 or a common fraction such as 1/1000. Whenever possible, it is better to enter the common fraction rather than a rounded decimal fraction: e.g., 1/1050 rather than .00095.

 

If I don't get some stuff on this might not get to take A2 maths, need some questions as well

Mr_Odwin Newbie

Mr_Odwin

Posted
Posted

So you are told to use the Poisson distribution as an approximation to the binomial. You are given all the stuf that you need by the look of it. The crux of the question seems to be

 

On the null hypothesis, how likely is it that a rate this great or greater could occur by mere chance?

 

It is talking about 7, or more, in 3000. One way to do this is to not work out the above question but to work out the probability of 6 or fewer. Then, one minus that is the same as the probability of 7 or more.

stuwii Newbie

stuwii

Posted
  • Author
Posted
So you are told to use the Poisson distribution as an approximation to the binomial. You are given all the stuf that you need by the look of it. The crux of the question seems to be

 

 

 

It is talking about 7, or more, in 3000. One way to do this is to not work out the above question but to work out the probability of 6 or fewer. Then, one minus that is the same as the probability of 7 or more.

 

Seems the gist of the questions will be the operation of this formula in numerical and real life situations

Fierce_LiNk Newbie

Fierce_LiNk

Posted
Posted
So.... is this to help you get back your lost FIFA save file, or what?

 

I never use the Thanks button, but I used it for that post. I was literally in tears and I swear that it felt like my insides were about to fall out.

 

On topic: Grunch and Odders. That is all ye need. Do you need to know this stuff before you take A2? Or are you doing it now? I was a little confused reading your wall of headache.

mcj metroid Newbie

mcj metroid

Posted
Posted
Need some resources linked to s2 for a2 maths. The poisson as an approximation to the binomial.

 

This page need be used only for those binomial situations in which n is very large and p is very small. For example: The null hypothesis holds that a certain genetic characteristic will express itself in p=.001 of the population. In a sample of n=3000 subjects, k=7 are observed to display the characteristic, whereas only np=3 are expected. On the null hypothesis, how likely is it that a rate this great or greater could occur by mere chance? Your computer would not be able to perform the factorial and exponential operations required for direct calculation (Exact Binomial Probability Calculator), and np<5 would preclude use the normal approximation (Binomial z-Ratio Calculator).

 

In cases of this sort, the appropriate binomial probabilities can be approximated by way of the Poisson probability function

 

TP(k out of n) = (e—np)(npk)

 

k!

where:

e = the base of the natural logarithms;

n = the number of opportunities for event x to occur;

k = the number of times that event x occurs or is stipulated to occur; and

p = the probability that event x will occur on any particular occasion;

 

Application of the Poisson function using these particular values of n, k, and p, will give the probability of getting exactly 7 instances in 3000 subjects. Applying it to all values of k equal to or greater than 7 will yield the probability of getting 7 or more instances in 3000 subjects, while applying it to all values of k equal to or smaller than 7 will give the probability of getting 7 or fewer instances in 3000 subjects. Note, however, that these results are only approximations of the true binomial probabilities, valid only in the degree that the binomial variance is a close approximation of the binomial mean.

 

To perform calculations of this type, enter the appropriate values for n, k, and p (the value of q=1—p will be calculated and entered automatically). Then click the 'Calculate' button. To enter a new set of values for n, k, and p, click the 'Reset' button. The value entered for p can be either a decimal fraction such as .001 or a common fraction such as 1/1000. Whenever possible, it is better to enter the common fraction rather than a rounded decimal fraction: e.g., 1/1050 rather than .00095.

 

If I don't get some stuff on this might not get to take A2 maths, need some questions as well

jesus it's like reading an edge review

Mr_Odwin Newbie

Mr_Odwin

Posted
Posted
I would help, but I systematically erased all memories I had of S2 from my brain.

 

Statistics kills maths.

 

*Is offended.*

 

Probability/Statistics is just as beautiful as other fields in mathematics. It's not all hypothesis testing.

Iun Apprentice

Iun

Posted
Posted (edited)

The real heart of the problem is this: How is this going to get you laid?

 

I have a similar question:

 

If x = y with a remaining factor of 3.7 - the cost of chicken pi, then what is z when v = 7z-underpants x 3yx?

 

The correct answer is, you're going home alone, Maths Boy.

Edited by Iun
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