Standard deviation and how it is calculated.

standard deviation is the deviation or the range a value could be from the mean. in a graph you will see a plus or minus a certain number which represents how much below and above the value on the graph the mean could lie. if two bar graphs have ranges that overlap then there is no statistical difference between the two numbersâ€¦we probably are going to get more into this later though

You will not be asked to calculate standard deviation, but you may be asked to recognize it or describe what it means if a groupâ€™s scores show a large or small standard deviation.

Standard deviation is a measure of how much a set of scores varies or deviates from the average.

Scores for a group with a large standard deviation has a lot of variation between them and the groupâ€™s mean. Scores for a group with a small standard deviation are more similar to the groupâ€™s mean.

A difference between means, even if large, is more meaningful if the standard deviation is small. If the standard deviation is large, it makes it less likely that a difference between means signifies anything.