chpt 9

• Population


  The entire group under study as defined by research objectives
• Census


  An accounting of the complete population, requires information from everyone in the population
• Populations


  • All people living in the US
  • All people living in the UAE
  • Emiratis living in the UAE
  • Youth living in the middle east
• Sample frame


  A master source of sample units in the population, a group of components from where we sample
• Sample frame error


  The degree to which the sample frame fails to account for all of the population

  
• Sample


  A subset of the population that suitably represent the entire group
• Sample unit


  The basic level of investigation
• Probability samples


  • Ones in which members of the population have a known chance (probability) of being selected into the sample, representative
• Non-probability samples


  • Instances in which the chances (probability) of selecting members from the population into the sample are unknown, non-representative

  
• Simple random sampling


  1. The probability of being selected into the sample is "known" and equal for all members of the population

  2. Uses a random device method to assure every member has the same chance of being included
• Systematic sampling


  Selects a random sample from a directory or list using a skip interval
• Cluster sampling


  Divides the population into subgroups called "clusters", then uses simple random sampling to select clusters
• Stratified sampling


  Divides the population based on different characteristics, then uses simple random sampling in each group
• With nonprobability sampling, selection is not based on fairness, equity, or equal chance and does not follow the theory of probability</b>
• Nonprobability sampling methods


  • Convenience sampling
  • Chain referral or snowball sampling
  • Judgmental or Purposive sampling
  • Quota sampling

  
• Nonprobability sampling should be avoided in scientific and market research where we want to generalize results to the entire population
• When writing a research report, a researcher needs to specify by which characteristics the sample is representative