What is the definition of population and a sample?
Population - The set of things you are interested (e.g. the population of the UK)
Sample - A subset of a population (e.g. everyone in the UK who are students)
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What is the definition of parameters and statistics?
Parameter - A number that describes the entire population
Statistic - A number taken from a sample. You can use this or a set of these to estimate the parameter.
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What is simple random sampling?
1. Get a list of the population and number them.
2. Select the amount you want and gather that amount of random numbers from a random number generator.
3. Match up the numbers to the list and take the sample
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What is systematic sampling?
Find a sample size n from a population N by taking one member from the first k members of the population at random then select every kth member after that using k = N/n
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What is Stratified Sampling?
If you want distinct groups to be represented in a sample, split the population into these groups and then sample within each group according to its size.
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What is opportunity sampling?
Take samples from members of the population you have access to until you have the sample of the desired size.
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What is Quota sampling?
When you want distinct groups to be represented in the sample, decide how many of each group you wish to have represented in advance and use opportunity sampling until you have the sample size for each group.
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What is Cluster sampling?
Split the population into clusters which are similar to each other and take a sample from each of these clusters.
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What does it mean if a sampling method is biased?
Creates a sample that does not represent the population at large.
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What is the difference between discrete and continuous data?
Discrete - Take any one of a finite set of categories but nothing within those values. E.g. only whole numbers from 1-10.
Continuous - Always numeric and can take any value between the two points. E.g. any number from 1-10 (can include decimals).
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What is the equation that finds the mean of a value? (x̄)
Mean = x̄ = Σx/n
or Σfx/Σf
For each x is a data value, f is the requency of each x and n is the total number of data values.
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What does variation mean?
How spread out data is from the mean. Standard deviation and variance both measure this.
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What is the equation for variance?
Σfx^2/Σf - x̄^2
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How do you find standard deviation?
Take the square root of the variance.
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Other cards in this set
Card 2
Front
What is the definition of parameters and statistics?
Back
Parameter - A number that describes the entire population
Statistic - A number taken from a sample. You can use this or a set of these to estimate the parameter.
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