9.1 Sampling Distributions

This is an awesome picture for understanding the differance between bias and variability.  As you see in A you are aiming for the center and it is up and to the right.  It has a high bias because you are missing target but there is no variability because they are all together.  B shows the opposite where it is a large spread and the dots are everywhere and surounding the center.

Lets try a practice problem with looking at a graph of this concept.

State with each one, if it has a high bias, high variablity or neither.
(answers are at the end of this page.)

Main Idea

The main idea with this section is the idea of taking many samples and then making data and histograms with that data.

For instance you count the number of green M&Ms in a bag.  You do this several times and take those numbers and plot them in a histogram.  So you have two bags with six.  Four bags with eight and so on.  This making a histogram, which will allow you to see patterns and understand where true mean average is and to see if there is anything wrong with your experiment by looking for variablity and bias.
 

Answers: A) high bias and high variablity.  B) Good data! C) High Variablity D) High Bias
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