| Standard Deviation Calculation |

| | According to Drummond and Jones (2006), a **standard** **deviation** "is the numerical value that describes the spread of scores away from the mean and is expressed in the same units as the original scores. |

| | A **standard** **deviation** is calculated by subtracting the mean of a distribution from the value of each individual variable in the distribution, squaring each resulting difference, summing these squared differences, then dividing this sum by the number of variables, and finally taking the square root of this quotient. |

| | When we have a small sample (typically 20 or fewer variables) it is generally recommended that we substitute n-1 for n so that the **standard** **deviation** is not underestimated. |

| faculty.tamu-commerce.edu /crrobinson/517/sdcalc.htm (419 words) |