Unit 9 - Lesson 6-7

Question 1

How do you find the variance of the sampling distribution of your sample mean?
(the variance of the distribution you’d get if you took multiple samples)

Answer 1

σx̄^2 = σ^2/n

(the x bar is in subscript right after the var)
n is # of trials, σ^2 is variance

Question 2

How do you find the standard error (basically the SD) of the sampling distribution of your sample mean?
(the variance of the distribution you’d get if you took multiple samples)

Answer 2

σx̄ = σ/√n

(the x bar is in subscript right after the var)
n is # of trials, σ is SD/SE
You can think of it like this: the SE of the variance of the sampling distribution of the sample mean is just the square root of the variance (from flash card 1)

Question 3

What is the mean of the SAMPLING distribution if you’re not given it?

Answer 3

It is the same as the population. It probably won’t be completely accurate, but it’s the best guess for the sample distribution’s mean.

For example, if Lucille has a collection of more than
500 songs on her phone that have a mean duration of
215 seconds, the mean of the sampling distribution is also 215.

Remember that the SAMPLING distribution is the distribution of multiple SAMPLES of the population (though I believe the best guess for a sample distribution’s mean would also be the population mean).