Data Collection

    Cards (43)

    • Define Population:
      The whole set of items that are of interest
    • Define Raw Data:
      Data obtained from a population
    • Define Census:
      Data that measures every member of a population
    • Define Sample:
      A selection of observations taken from a subset of the population used to estimate information about the population as a whole
    • Outline the advantage of a census:
      • It gives a completely accurate result
    • Outline the disadvantages of a census:
      • Time consuming
      • Expensive
      • Cannot be used when the testing process destroys the items
      • It is difficult to process a large quantity of data
    • Outline the advantages of a sample:
      • Less time consuming
      • Cheaper
      • Fewer responses are needed
      • Less data is processed
    • Outline the disadvantages of a sample:
      • Data may not be as accurate
      • The sample may not be large enough to be representative of the whole population
    • Define Sampling Units:
      The individual units of a population
    • Define Sampling Frame:
      Sampling units individually named or numbered to form a list
    • Name the three types of random sampling:
      • Simple random sampling
      • Systematic sampling
      • Stratified sampling
    • Define Simple random sampling:
      A sampling technique where every element in the set has an equal chance of being selected
    • Define Systematic sampling:
      A sampling technique where the elements are chosen at regular intervals from an ordered list
    • Define Stratified sampling:
      A sampling technique where the population is divided into exclusive strata and a random sample is taken from each
    • Outline the advantages of simple random sampling:
      • Non-bias
      • Easy and cheap for small samples and populations
      • Each sampling unit has a known and equal chance of being selected
    • Outline the disadvantages of simple random sampling:
      • Not suitable for large samples and populations
      • Sampling frame needed
    • Name the two methods of choosing the numbers from a sampling frame in simple random sampling:
      • Generating random numbers
      • Lottery sampling
    • Describe how a calculator is used for generating random numbers for simple random sampling:
      Each sampling unit from a sampling frame is numbered.
      Use a calculator to generate a set of numbers.
      Select the sampling units who correspond to the numbers generated.
    • Describe how lottery sampling is used for simple random sampling.
      The sampling units from a sampling frame are written on identical cards.
      The cards are put into a hat.
      The required number of sampling units needed are drawn from the hat.
      The card of the sampling unit drawn out are selected.
    • Outline the advantages of systematic sampling:
      • Simple and quick to use
      • Suitable for large samples and populations
    • Outline the disadvantages of systematic sampling:
      • Sampling frame needed
      • Can be biased if the sampling frame is not random
    • The formula for how to work out the value of the regular intervals for systematic sampling:
      The population / the sample size
    • The first person selected in systematic sampling is chosen randomly, then the regular intervals continue
    • Outline the advantages of stratified sampling:
      • Accurately reflects population structure
      • Guarantees proportional representation of all groups within a population
      • analyse specific groups within a population
      • observe relationships between groups
    • Outline the disadvantages of stratified sampling:
      • The population must be clearly classified into distinct strata
      • Same disadvantages as simple random sampling within each stratum
    • Name the two types of non-random sampling:
      • Quota sampling
      • Opportunity sampling
    • Define Quota sampling:
      A sampling technique where the sample selected reflects the characteristics of the whole population
    • Define Opportunity sampling:
      A sampling technique where the sample is taken from people who are available at the time of study and who fits the criteria needed
    • Outline the advantages of quota sampling:
      • Allows a small sample to be representative of the whole population
      • No sampling frame needed
      • can be quick
      • can be easy
      • can be cheap
      • Allows comparisons between different groups within the population
    • Outline the disadvantages of quota sampling:
      • Bias
      • The population must be divided into groups which can be inaccurate - not possible to estimate sampling errors
      • A more in depth study can be time consuming as it increases the number groups
      • Non-responses are not recorded
    • Outline the advantages of opportunity sampling:
      • Easy
      • Cheap
    • Outline the disadvantages of opportunity sampling:
      • Results can be unrepresentative of the whole population
      • Highly dependent on the individual researcher
    • Define Qualitative data:
      Non numerical data
    • Define Quantitative data:
      Numerical data
    • Define Discrete data:
      Data which can only take specific values
    • Define Continuous data:
      Data which can take any value in a given range
    • What is the limitation for continuous data?
      How accurately it is measured
    • Define Class boundaries:
      The maximum and minimum values in each group
    • Define the Midpoint:
      The mean/ average of the class boundaries
    • Define the Class Width:
      The difference between the upper and lower class boundaries
    See similar decks