Data sampling

• what are the different types of random sampling

  simple random,stratified, systematic
• what are the two types of non-random sampling

  quota sampling, opportunity sampling
• define a population

  a whole set of items
• define a census

  a measure of every member in a population
• what is quantitative data

  numerical data
• what is a qualitative data

  non-numerical data
• what are the pros of a simple random sample

  free of bias, easy and cheap for small samples,each sampling unit has an equal chance if selection
• what are cons of simple random sampling

  unsuitable for large samples,sampling frame needed
• what are pros/advantages of systematic sampling

  simple and quick, suitable for large samples
• what are cons of systematic sampling

  sampling frame needed, bias is introduced if frame isnt random
• number sampled in a population = number in strata/number in population x sample size
• what are the pros of a stratified sampling

  accurately reflects population structure,proportional representation of a group within a population
• what are cons of stratified sampling

  population has to be placed in clear distinct strata, sampling frame needed for each stratum, bias if frame isnt random
• what are the pros of quota sampling

  no sampling frame needed, quick easy and inexpensive, allows a small sample to be a valid representation of the population
• what are cons of quota sampling

  bias, population has to be divided into different groups which is costly and sometimes inaccurate, non-responses not recorded,
• what are pros of opportunity sampling

  easy + inexpensive
• what are cons if opportunity sampling

  it isn't an accurate representation of the population, dependent on individual researcher