What is Standard Deviation?

• How far from the mean are most of the data?
• Shows the data spread

x = Value of data x (with the dash on top) = sample mean n = number of data points

How to find Standard Deviation

• Step 1: Find the mean
• Step 2: For each data point, find the square of its distance to the mean (aka - the square of the difference)
• Step 3: Sum the values from Step 2
• Step 4: Divide by the number of data points - 1
• Steps 5: Take the square root

Standard Deviation Overlap

Standard deviation overlap (Black Bars)

What is Standard Error

• Description of precision
• Where is the real mean most likely?