Standard Deviation Part 1

So far, we have had a look at the formula for standard deviation. In this activity, we are going to learn what standard deviation is and how we are going to use it in data analysis.

An average (mean) does not give us enough information for all of the analysis we might be doing.

Let’s start with a data set variable that has a mean of 13.25.
(M = 13.25)

An average does not tell us where most scores are located – we know that most scores won’t be at the average, but when using all of the scores in the data set, we get an average of 13.25.

To get an idea of where most of the data points lie, we apply standard deviation. The standard deviation tells us where scores are relative to the mean.

In the above image, we see a histogram of data points with a mean of 13,25. In this histogram, we can see that most scores are not at the mean, but they are spread out a little more.

In the above image, we can see that the average of the bulk of the data points is spread out by approximately 1,11 points from the mean. This means that we have a standard deviation of 1,11 from the mean.

Let’s have a look at a different example:

In the above example, the standard deviation from the mean is 2,22. What this means is that most scores fall within approximately 2 points from the mean.