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Making Deviation Standard

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Resources for this lesson:

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Andrew, Justyce, and KhalidAndrew and Khalid are still confused about how to calculate the standard deviation. Justyce suggests they watch a short video for one more example. If you are still confused, take time to watch the video.

Sample standard deviation and bias (from Khan Academy)

There is a basic formula for finding the standard deviation. Follow each step below to discover this formula.

  • STEP 1: Calculate the mean of the data. The symbol used for mean is x.
  • STEP 2: Subtract each data point from the mean, square the differences, and add the differences together. The symbol used for each data point is  for n data points.

Check Your Understanding

  • STEP 3: Divide the sum by the number of data points.

Check Your Understanding

  • STEP 4: Take the square root of the quotient arrived at in Step 3.

The square root of a fraction where the numerator is the quantity of the mean minus x sub 1 squared plus the quantity of the mean minus x sub 2 squared plus the quantity of the mean minus x sub 3 squared plus the quantity of the mean minus x sub 4 squared plus the quantity of the mean minus x sub 5 squared plus the quantity of the mean minus x sub 6 squared plus ellipsis plus the quantity of the mean minus x sub n squared. The denominator is n.

This is the formula for finding the standard deviation of a set of data.

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