Measures of Variation with Unicorn Example

We are just studying the endurance of these forty children. So these 40 values are _.

We can find the range by first sorting the data. Sort(Feet) = {160, 420, 440, 480, 520, 560, 580, 640, 660, 660, 680, 740, 740, 760, 760, 820, 820, 940, 1100, 1120, 1140, 1160, 1200, 1240, 1260, 1260, 1320, 1340, 1360, 1500, 1500, 1500, 1540, 1620, 1760, 1880, 1940, 2000, 2180, 2960} The range is the greatest value minus the least value. So the range distance these children will run after Klapheck riding a unicorn is _ _.

Is this range a parameter or a statistic?

To find standard deviation of a population in GeoGebra we can use either SD( population ) or stdevp( population ) To find variance of a population in GeoGebra use Variance( population ). Or just square the standard deviation. Find standard deviation for the distance this population of children will follow a unicorn.

Find variance for the distance this population of children will follow a unicorn.

If we were studying the endurance of children in USA, then what is the population and sample?

Previously when computing numbers it did not matter whether the data was a sample or a population. For standard deviation and variance it does matter. If we used the same method to find a sample's standard deviation and variance we would get numbers that were too small on average. To find standard deviation of a sample in GeoGebra we can use either SampleSD( sample ) or stdev( sample ) To find variance of a sample in GeoGebra use SampleVariance( sample ). Or just square the standard deviation. Find standard deviation for the distance this sample of children will follow a unicorn.

Find variance for the distance this sample of children will follow a unicorn.

For a sample of numbers { 1, 2, 3, 4, 4} find the three measures of variance.

For a sample of colors { green, green, white, yellow, yellow } find the variation.

For which measurements will the numerical result be different if our data is a sample versus a population?