Question about Variables?

jeanlovesmath

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Mar 4, 2015
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Hey guys,

So it has been a while since I've done any statistics but it's one of the compulsory papers for my course D: We looked at variables today and I got a bit confused with my lecturer's notes:


Under "Variables", he said that "Variables are usually denoted by capital Roman letters e.g. X, Y, Z" and "Measurements on these variables are usually denoted by lower case Roman letters, often indexed by a counter" - this makes sense but then...

Under "Sampling", he said that "A sample consists of n measurements from a population on variable X. The measurements can be denoted X1, X2, etc" and "The sample values are denoted x1, x2... xn and n is called the sample size"

What is the difference between the measurements that are denoted "X1, X2, etc" and the sample values that are denoted "x1, x2... xn"?

Thanks in advance guys :eek:
 
Hey guys,

So it has been a while since I've done any statistics but it's one of the compulsory papers for my course D: We looked at variables today and I got a bit confused with my lecturer's notes:


Under "Variables", he said that "Variables are usually denoted by capital Roman letters e.g. X, Y, Z" and "Measurements on these variables are usually denoted by lower case Roman letters, often indexed by a counter" - this makes sense but then...

Under "Sampling", he said that "A sample consists of n measurements from a population on variable X. The measurements can be denoted X1, X2, etc" and "The sample values are denoted x1, x2... xn and n is called the sample size"

What is the difference between the measurements that are denoted "X1, X2, etc" and the sample values that are denoted "x1, x2... xn"?

Thanks in advance guys :eek:
My understanding is the following:
Suppose our variables are gum ball machines and the measurements are the number of gum balls. Then X1 is gum ball machine number 1 and x1 is the number of gum balls it has; X2 is gum ball machine number 2 and x2 is the number of gum balls it has and so forth. So a capital letter is the thing (whatever it is) from the population (the gum ball machine) and the small letter is how much (the value) of what the capital letter has (how many gum balls).

Note that there does not have to be a specific thing attached to the variable or measurement, we can just call X1 the number one X and x1 the value of X1.
 
My understanding is the following:
Suppose our variables are gum ball machines and the measurements are the number of gum balls. Then X1 is gum ball machine number 1 and x1 is the number of gum balls it has; X2 is gum ball machine number 2 and x2 is the number of gum balls it has and so forth. So a capital letter is the thing (whatever it is) from the population (the gum ball machine) and the small letter is how much (the value) of what the capital letter has (how many gum balls).

Note that there does not have to be a specific thing attached to the variable or measurement, we can just call X1 the number one X and x1 the value of X1.

Thanks heaps!! Makes sense now :)
 
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