Descriptive Statistics Flashcards

1
Q

Define measures of central tendency?

A

These inform us about the centre of the data

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2
Q

What are the 3 measures of central tendency?

A

Mean, median, mode

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3
Q

How do you calculate the mean?

A
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4
Q

What are the advantages of using the mean?

A

It is a ver sensitive statistic because it takes into account the exact value of all the data
It is representative of all of the data

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5
Q

What are the disadvantages of using the mean?

A

If one of extremely high or low (an anomaly) then the mean can be distorted and therefore misrepresent the data
It can be used with nominal data

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6
Q

How do you calculate the median?

A

The middle value in an ordered list. All data must be ordered numerically in a list. If there is an even number of data then you get the 2 central items add them and then divide by 2 to get the median

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7
Q

What are the advantages of using the median?

A

It isn’t effected by extreme scores so it can be useful under such circumstances
It is easy to calculate
It isn’t distorted by any anomalies

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8
Q

What are the disadvantages of using the median?

A

It doesn’t reflect the whole data set
It is less sensitive than the mean because exact values may not always be used

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9
Q

How do you calculate then mode?

A

The most frequent value
You can have data sets with bi or tri modal data sets

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10
Q

What are the advantages of using the mode?

A

It is unaffected by anomalies
It is useful for discrete data
The only measure of central tendency that can be used for nominal data
It’s output is a piece of data, you can’t have 2.4 children

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11
Q

What are then disadvantages of using the mode?

A

Sometimes there maybe too many modes that using it becomes meaningless
It doesn’t represent the full data set

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12
Q

Define measures of dispersion?

A

A type of descriptive statistic that finds out how spread out the data items are

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13
Q

What are the 2 measures of dispersion?

A

Range
Standard deviation

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14
Q

Define the range?

A

the arithmetic distance between the top and the bottom values in a set of data

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15
Q

What are the advantages of using the range?

A

It is easy to calculate
Even if 2 sets of data have the same mean they could have different ranges so the range can be used well to describe the data

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16
Q

What are the disadvantages of using the range?

A

It is effected by extreme values
If fails to take into account the distribution of the numbers (eg 1,2,72)
Could use IQR

17
Q

Define standard deviation?

A

The standard deviation is a more precise way of measuring the spread of the data. It is the measure o9f the average distance between each data item and the mean (ignoring plus and minus values)

18
Q

What does a small standard deviation mean?

A

The data set is quite compact

19
Q

What are the advantages of using the standard deviation?

A

Precise measure of dispersion because it takes into account all values

20
Q

What are the disadvantages of standard deviation?

A

It may hide some of the characteristics of the data set eg extreme values

21
Q

Why do you add 1 onto the range?

A

To avoid rounding errors