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#1 2012-11-29 19:39:17

123ronnie321
Member
Registered: 2010-09-28
Posts: 128

probabilty distribution

Hi

I want to simulate a real world problem. People can enter a bank at any time between 8 am  and 5 pm in the evening. More people are likely to come in the peak morning hours. So how do I get a distribution function for such a case.

I am looking for general ways of tackling this problem and not for a particular solution. I know basic probability but have very limited knowledge in statistics (know just basics like normal distribution, mean, variance)

And good to be back here after a long time smile

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#2 2012-11-29 19:50:26

bob bundy
Moderator
Registered: 2010-06-20
Posts: 6,256

Re: probabilty distribution

hi 123ronnie321

Welcome back!

You could use a normal distribution and fit it to your data.  Strictly it would be possible to get values outside the range, but, in practice, there's a very low chance of this ... if you set 8am as say 3 x the standard deviation.  You'd have to firm up on what you mean by 'the peak morning hours'.

Or you could make sure that you don't go outside the limits by having a straight line from (8,0) to a maximum point, and then another sloping down from there to (17,0).

Fix the height so that the area of that triangle is equal to 1.

Bob


You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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#3 2012-11-29 20:07:31

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 82,610

Re: probabilty distribution

Hi 123ronnie321;

Queuing problems like arrivals at a bank with waiting times and things like that are sometimes best modelled with the Poisson Distribution. If you have the data and know what you want to compute probabilities of take a look here and see if any of the model problems are close to what you want.

http://www.umass.edu/wsp/statistics/les … index.html


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

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#4 2012-11-30 02:42:50

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,859

Re: probabilty distribution

Hi bobbym

Thanks for the link!


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#5 2012-12-01 01:46:36

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 82,610

Re: probabilty distribution

Hi anonimnystefy;

You have been expressing an interest in statistics so you are welcome.


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

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#6 2012-12-01 03:49:55

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,859

Re: probabilty distribution

Kind of...


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#7 2012-12-01 08:24:12

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 82,610

Re: probabilty distribution

Remember the other thread where we talked about careers...


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

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#8 2012-12-01 10:17:10

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,859

Re: probabilty distribution

I do. But, I think it would be good for me to do more problems in statistics...


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#9 2012-12-01 10:24:34

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 82,610

Re: probabilty distribution

Where are you at the moment?


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

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#10 2012-12-01 10:37:45

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,859

Re: probabilty distribution

Home...


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#11 2012-12-01 10:39:24

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 82,610

Re: probabilty distribution

I meant where are you in statistics?


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

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#12 2012-12-01 10:42:00

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,859

Re: probabilty distribution

You should've been more precise.

I know something about distibutions, mean, variance,... But that's about it...


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#13 2012-12-01 10:43:58

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 82,610

Re: probabilty distribution

Anything I can help with or you still want to research more?


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

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#14 2012-12-01 10:47:22

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,859

Re: probabilty distribution

I cannot think of a better way to learn something new than through problems...


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#15 2012-12-01 10:48:17

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 82,610

Re: probabilty distribution

Are you doing any problems right now?


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

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#16 2012-12-01 10:51:19

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,859

Re: probabilty distribution

No. I don't know where to find them... Do you have any links?


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#17 2012-12-01 11:08:21

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 82,610

Re: probabilty distribution

http://stattrek.com/statistics/problems.aspx

They put a couple of problems at a time. You have enter different topics in the input boxes to get more.

Some of these tests look okay.

http://www.wiziq.com/tests/statistics

http://www2.gsu.edu/~dscbms/ibs/qcontent.html

http://www.tc3.edu/instruct/sbrown/stat/pracprob.htm

I have some shopping to do, see you later and good luck with the problems.


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

Offline

#18 2012-12-01 11:56:31

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,859

Re: probabilty distribution

Thanks for the links. I will look at them.


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#19 2012-12-01 15:41:02

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 82,610

Re: probabilty distribution

Hi;

Let me know if you get stuck.


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

Offline

#20 2012-12-01 20:09:21

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,859

Re: probabilty distribution

I have a question. Is a roll of two dice modeled wirh a descrete normal distribution?


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#21 2012-12-01 20:16:01

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 82,610

Re: probabilty distribution

I use a binomial distribution. What is the problem?


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

Offline

#22 2012-12-01 20:21:46

anonimnystefy
Real Member
From: The Foundation
Registered: 2011-05-23
Posts: 14,859

Re: probabilty distribution

Just asking. It's not in any of those...


“Here lies the reader who will never open this book. He is forever dead.

“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

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#23 2012-12-01 20:24:49

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 82,610

Re: probabilty distribution

I use about 5 or 6 distributions mostly and if you want I can show what type of problems they solve.


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

Offline

#24 2012-12-04 08:53:55

123ronnie321
Member
Registered: 2010-09-28
Posts: 128

Re: probabilty distribution

Thanks for the links. Khan academy has some really good videos on statistics.

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#25 2012-12-04 13:19:52

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 82,610

Re: probabilty distribution

Hi 123ronnie321;

They do have some nice videos!


In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

Offline

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