# OCR MEI Statistics 1

How do we calculate the Median?
(n+1)/2. The middle of the range of results. Using this formula gives us the position of the value i.e. (29+1)/2 = 15th value.
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How do we calculate the Mean?
Total value of data, x/ number of values, f.
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What is the Mode of a data set?
The number in the data set that appears the most. For example, 1, 2, 14, 16, 17, 17, 17, 19, 22, 22. The mode = 17.
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How do we calculate Range?
Maximum value - minimum value.
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How do we calculate 'Upper quartile' and 'Lower quartile'?
UQ = 3(n+1)/4 or 3/2*range. LQ = (n+1)/4 or 1/2*range.
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How do we calculate Inter-quartile range?
UQ - LQ
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What is one advantage and one disadvantage of using Median and IQR?
Adv; Less affected by skew and outliers. D'adv; Don't use the majority of data in calculations.
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One advantage and one disadvantage of using Mean and Root Mean Square Deviation.
Adv; Uses larger range of data. D'adv; More affected by skew and outliers.
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When can a data value be classed as an outlier?
If the data value is >1.5 IQRs beyond the UQ or LQ, it is classed as an outlier.
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Equation for outliers.
Less than (LQ-1.5*IQR) or more than (UQ+1.5*IQR)
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When the outlier is a clear error in the recording of data i.e. Data= "Age of people passing their driving test". A 2 year old can be discarded but a 58 year old cannot be.
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Do you know the rhyme?
Hey diddle diddle, the median's in the middle, you add and divide for the mean. The mode is the one that is the most, and the range is the bit in between.
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## Other cards in this set

### Card 2

#### Front

How do we calculate the Mean?

#### Back

Total value of data, x/ number of values, f.

### Card 3

#### Front

What is the Mode of a data set?

### Card 4

#### Front

How do we calculate Range?

### Card 5

#### Front

How do we calculate 'Upper quartile' and 'Lower quartile'?