# core maths

what is the formula for a stratified sample?
Number in the group/ total population x sample size
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what is the mode?
The most common number
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What is the median?
The middle value when the values are in size order
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What is the mean?
The total of all the items/number of items
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What is the range?
The difference between the highest and lowest value
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What is qualitative data?
Data that uses words
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What is quantitative data?
Data that uses numbers
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What is discrete data?
Data that can only take certain exact values (e.g. shoe size)
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What is continuous data?
Data that can be taken at any value in a range (e.g. foot length, you will always be able to measure it more accurately)
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What is the formula for the lower quartile?
(n+1)/4 (n being the total number of values)
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What is the formula for the upper quartile?
3(n+1)/4 (n being the total number of values)
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What is the formula for frequency density?
frequency/class width
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What is the modal class?
The class in a grouped frequency table that has the highest frequency
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Advantage: shows how spread the data is or easy to calculate Disadvantage: only uses the first and last pieces of data
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Advantage: Not influenced by extreme values Disadvantage: Doesn't use all the data
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Name one advantage of using standard deviation
Advantage: uses all the pieces of data Disadvantage: complicated to calculate/time consuming to calculate
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What is a cluster sample?
When a group is selected at random and data is collected from that 'cluster'
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What is quota sampling?
When the sampler selects a specific number of people from a stratum
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## Other cards in this set

### Card 2

#### Front

what is the mode?

#### Back

The most common number

### Card 3

#### Front

What is the median?

#### Back ### Card 4

#### Front

What is the mean?

#### Back ### Card 5

#### Front

What is the range?

#### Back 