Distribution of balls in a box (with a twist)

AI Thread Summary
The discussion centers on the distribution of two differently sized colored balls, red and blue, in a box. It explains that the overall size distribution can be described as a weighted average of the individual probability density functions (PDFs) for each color, based on their proportions in the total. This combined distribution is referred to as a "mixture distribution," allowing for the probability of selecting a ball of any size without regard to its color. Participants clarify that the size distribution is relevant to understanding the overall mixture. The conversation emphasizes the importance of recognizing how different distributions interact when combining multiple sets of data.
Apteronotus
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Suppose I have an box (set) containing two different colored balls, red and blue, say.

Now, suppose the balls differ in size, where the size of the red balls has one particular distribution and those of the blue another.

How can we describe the distribution of the balls in the box?
 
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Your description is confusing. What has size got to do with the distribution?
 
Apteronotus said:
Suppose I have an box (set) containing two different colored balls, red and blue, say.

Now, suppose the balls differ in size, where the size of the red balls has one particular distribution and those of the blue another.

How can we describe the distribution of the balls in the box?
It's a weighted average of the PDF_red and PDF_blue, with weights proportional to the fraction of each color:

PFD_total = (num_red/total_num) * PDF_red + (num_blue/total_num) * PDF_blue
 
mathman said:
Your description is confusing. What has size got to do with the distribution?

I'm interested in the distribution of the sizes.
 
FactChecker said:
It's a weighted average of the PDF_red and PDF_blue, with weights proportional to the fraction of each color:

PFD_total = (num_red/total_num) * PDF_red + (num_blue/total_num) * PDF_blue

So would it be a "mixed distribution"?
 
Apteronotus said:
So would it be a "mixed distribution"?

It is a single distribution where a ball can be picked at random by a blind person and it would give the probability distribution of the size, without knowing the color. It combines the two distributions into one.
 
Apteronotus said:
So would it be a "mixed distribution"?
Yes. That is called a "mixture distribution".
 
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