Standard Deviation

• What is the first step in calculating standard deviation?

  Work out the total of x (e.g. volume of oxygen in cm cubed)
• Why do you divide the total of x by the number of repeats?

  To calculate the mean of the data set
• If the mean of x is 4.3 and x is 5.5, what is x - mean?

  1. 2
• What do you calculate after finding x - mean?

  Calculate (x - mean) squared
• What is the next step after calculating (x - mean) squared?

  Work out the total of (x - mean) squared
• What formula do you use to find the standard deviation?

  Square root of (x - mean) squared / (n - 1)
• What does a high standard deviation indicate about the data?

  The data is less precise
• What does small or no error bars indicate about the data?

  The data is repeatable/reproducible
• In the formula for standard deviation, what does n represent?

  The number of repeats
• What does standard deviation measure?

  The spread of data around a mean
• What is a benefit of using standard deviation in data analysis?

  It takes into account all the data
• What are the steps to calculate standard deviation from a set of data?

  1. Work out the total of x
  2. Divide the total of x by the number of repeats to find the mean
  3. Calculate x - mean
  4. Calculate (x - mean) squared
  5. Work out the total of (x - mean) squared
  6. Calculate standard deviation using the formula: square root of (total of (x - mean) squared / (n - 1))