Standard deviation

• What is the formula for standard deviation of a sample?

  S = $\sqrt{\frac{\Sigma(X - \bar{X})^2}{N}}$
• What does Σ represent in the standard deviation formula?

  It means "sum of"
• What does X represent in the standard deviation formula?


  Each value in the data set
• What does $\bar{X}$ represent in the standard deviation formula?


  The mean of all values in the data set
• What does N represent in the standard deviation formula?

  The number of values in the data set
• What can be concluded from overlapping error bars?

  • There is no significant difference
• What can be concluded from non-overlapping error bars?

  • There is a significant difference
• How do you calculate the top of the error bar?

  Add the standard deviation to the mean
• How do you calculate the bottom of the error bar?

  Subtract the standard deviation from the mean