Flashcards
Types Of Sampling
Cards in this deck (8)
- 1Random samplingRANDOM SAMPLING CHOOSES ITEMS AT RANDOM
1)In a random sample every person has an equal chance of being chosen
2) You need a full list of the population,so everyone has the same chance of being included
Pros: Every member of the population has an equal chance of being chosen, so it is completely unbiased and the sample should represent the population
Cons: It might not be convenient, it might be impossible to list the whole population or to access everyone - 2Method of random sampling1) Assign a number to every member of the sample frame
2)Use a computer, calculator etc. to create a list of random numbers
3) Finally match the numbers of the members in the sample frame to the numbers on the random list to create the sample. - 3Stratified sampling:1)Sometimes the population is made up of groups or categories e.g. age or gender
2)A stratified sample gives the different groups in the sample an amount of representation that is proportional to how big they are in the population- this means big groups get more and small groups get less
3)This is useful when the different groups are likely to give different results - 4Pros and cons of stratified sampling:pros: If you have easy to define categories in the population this is likely to give you representative sample, and you can compare results from different groups
cons: It isnt useful when you dont have obvious categories or when the categories are hard to define. It can be expensive because of the extra detail involved - 5Method of stratified sampling:1)Split the population into different categories
2) Calculate the number to sample from each category using (number in category/total number) X sample size
3) Use random sampling to choose the sample members from each category - 6systematic sampling1)You can use systematic sampling to generate your sample when the population is very large
2)It works by choosing a random starting point and then taking a sample at regular intervals afterwards
3)Its particularly good if you want a method to choose items for quality control checks on a mass production line because you can set the machines up so they sample every nth item - 7pros and cons of systematic samplingpros : Systematic sampling should produce an unbiased sample and can be carried out by machine
cons : The nth item might coincide with a pattern - e.g. if every tenth gizmo produced by a machine is faulty and you sample every tenth gizmo for quality control, your sample will either be completely faulty or completely without faults - either way the sample will be biased - 8cluster sampling1)Sometimes, in a large population you can pick out smaller groups called clusters - they're often based on criteria like location, e.g. towns within a country.
2)Cluster sampling is where a random sample of clusters is chosen, and then every member in those clusters is included in your sample .
3)The closer the distribution of members within the clusters is to the whole population, the less bias there will be in the sample.
4) For this type of sampling you only need a list of the clusters and the members in the sampled clusters
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- Flashcards on Types Of Sampling, created by xavier mirza on 10/01/2019.
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- xavier mirza
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