Sampling+L2

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=Sampling information:= == == 

**Standard Deviation and Variance**
The link for the clip I showed about variance is: []

Standard deviation and variance are just ways of measuring how spread out (or squished up) your data is. The standard deviation is probably the most common measure of spread used by statisticians (rather than the range or interquartile range). It is not that easy to interpret, but it does play a very important role in statistical theory, inference and decision making.

Really all we can do at this level is use the standard deviation to get a 'feel' for the size of spread in our sample. The standard deviation is zero only if there is no spread (that is, all the observations are identical). Also, for many unimodal, moderately symmetric sets of data the following rule gives us a reasonable idea of spread: Approximately · **68% ** of the data will lie within **1 ** standard deviation of the sample mean · **95% ** of the data will lie within **2 ** standard deviations of the sample mean
 * Interpreting the (sample) standard deviation **

Remember VARIANCE is just the STANDARD DEVIATION squared, so therefore the STANDARD DEVIATION is simply the square root of the VARIANCE.

For further information try: []

or any other basic statistics website