Measures of Variation

​What is the median?

• ​The value in the center of an ordered list of data. If 2 values appear in the center, it is the mean of those 2 values.

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​What is the range?

• ​The range is the difference between the highest and lowest data value.

​Quartiles

• ​Values that divide the data into 4 equal parts

​First and Third Quartiles

• ​The first quartile is the median of the data values less than the median.

• The third quartile is the median of the data values greater than the median.

​Interquartile Range

• ​The IQR is the difference between the first and third quartiles.

​Outliers

• ​Outliers are extremely high or low values in reference to the data set.

​Find the 1st and 3rd (or lower and upper) quartiles. Look at Step 2.

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​Once you have the first and third quartiles, you can find the IQR by subtracting them. Look at step 3.

https://www.youtube.com/watch?v=0TulXwT_3ck&t=26s​

​To find the "limits" of the outliers, take first quartile and subtract 1.5 x IQR, and then take the third quartile and add 1.5 x IQR. Watch and learn!

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​https://www.youtube.com/watch?v=UmKPdxlFAsI&t=211s

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