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QUAN 2010 Notes Introduction to Business Statistics

Handout Preview Activity: Sampling Distributions drawing from a Normal Population

Before we start formally learning about sampling distributions, I’d like you to explore to see what happens when we take random samples from a population and calculate sample means.
Use the applet below to draw samples from a normal distribution and explore how sample means behave.
To change the sample size, enter β€œ\(n=\#\)” for the number you want to be the sample size.
(This applet was made in GeoGebra by Steve Phelps.)
  1. The Population:
  2. The Sample Means: Choose a sample size, use the applet to generate many samples, and record what you observe.
    Sample Size (\(n\)) Approximate Mean of Sample Means (\(\mu_{\bar{x}}\)) Approximate Standard Deviation of Sample Means (\(\sigma_{\bar{x}}\))
    \(n=4\)
    \(n=20\)
    \(n=35\)
  3. Compare:
    • How does the average of the sample means compare to the population mean?
    • How does the spread of the sample means change as \(n\) increases?
    • How does the shape of the distribution of sample means change as \(n\) increases?
  4. Your Rule:
    Based on your observations:
    • The mean of the sampling distribution of the sample mean is about:
    • The standard deviation of the sampling distribution of the sample mean is about:
    (We’ll check your β€œrules” together as a class and compare them with the exact formulas.)