September 21 Lecture

# September 21 Lecture - Lecture Interquartile Range The...

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Lecture September 21, 2011

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Interquartile Range The interquartile range gives the distance covered by the middle 50% of the data. This is a ROBUST measure of spread as this is a measure of spread of the middle half of the observations (generally not affected by outliers). Formula: IQR = Q 3 –Q 1
Data: Which dataset has a higher • range? •I Q R ? Data 1: 1, 2, 3 Data 2: 1, 1, 1, 2, 3, 3, 3 Data 3: 100, 100.5, 101, 101.5, 102

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Range Calculation Data 1: 1, 2, 3 Data 2: 1, 1, 1, 2, 3, 3, 3 Data 3: 100, 100.5, 101, 101.5, 102
IQR Calculation Data 1: 1, 2, 3 Data 2: 1, 1, 1, 2, 3, 3, 3 Data 3: 100, 100.5, 101, 101.5, 102

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Deviation Definition in words: Definition numerically:
Deviation Example Consider the data: 1, 2, 3 Calculate the average deviation:

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Sample Question Pick 3 numbers. Calculate the average deviation. The answer is: A) 0 B) >0 C) <0 D) I just want the clicker mark. E) None of the above.
What's the problem!!!???

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How do we correct it?????
Another Measure of Dispersion-- Standard Deviation In words: the standard deviation is approximately the average distance the data values are from the centre.

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Standard Deviation The standard deviation is approximately, the average deviation.
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September 21 Lecture - Lecture Interquartile Range The...

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