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The idea of spread and standard deviation

See how distributions that are more spread out have a greater standard deviation.

Introduction to standard deviation

Standard deviation measures the spread of a data distribution. The more spread out a data distribution is, the greater its standard deviation.
For example, the blue distribution on bottom has a greater standard deviation (SD) than the green distribution on top:
A double dot plot with the upper half modeling the S D equals one and fifty nine hundredths and the lower half models the S D equals 2 and seventy nine hundredths. S D equals one and fifty nine hundredths dots range from 2 to 8 with a vertical line at around 5. The 2 and seventy nine hundredths dots range from 0 to 10 with a vertical line at around 5 and 25 hundredths.
Interestingly, standard deviation cannot be negative. A standard deviation close to 0 indicates that the data points tend to be close to the mean (shown by the dotted line). The further the data points are from the mean, the greater the standard deviation.

Try it yourself

Which of the data distributions shown below has the greater standard deviation?
Choose 1 answer:
A double dot plot with the upper half modeling Distribution A and the lower half models Distribution B. Distribution A dots range from 0 to 10 with a vertical line at around 5 and one half. Distribution B dots range from 4 to 9 with a vertical line at around 6 and one half.

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