Lesson 11: Sampling

• Sampling - A word that refers to your method or process of selecting respondents or people to answer questions meant to yield data for a research study.
• Population - The bigger group from where you choose the sample.

   
• Sampling Frame - Used to mean the list of the members of such population from where you will get the sample.
• History of Sampling

  The beginning of sampling could be traced back to the early political activities of the Americans in 1920 when Literacy Digest did a pioneering survey about the American citizens’ favorite among the 1920 presidential candidates.
• Two Classes of Sampling Strategy

  1. Probability Sampling or Unbiased Sampling
  2. Non-Probability Sampling
• Probability Sampling or Unbiased Sampling - Involves all members listed in the sampling frame representing a certain population focused on by your study.
• Sampling Error

  • Crops up if the selection does not take place in the way it is planned
  • The smaller the sample is, the bigger the number of sampling errors.
• Types of Probability Sampling

  • Simple Random
  • Systematic Sampling
  • Stratified Sampling
  • Cluster Sampling
• Types of Probability Sampling

  Simple Random - Is the best type of probability sampling through which you can choose sample from a population. Simple random sampling happens through any of these two methods:

  1. Have a list of all members of the population.
  2. Have a list of all members
• Types of Probability Sampling

  Systematic Sampling - For this kind of probability sampling, chance and system are the ones to determine who should compose the sample.
• Types of Probability Sampling

  Stratified Sampling - The sample is chosen in a way that such group is liable to subdivision during the data analysis stage.

   
• Types of Probability Sampling

  Cluster Sampling - It makes you isolate a set of persons instead of individual members to serve as sample members.
• Non-Probability Sampling - Disregards random selection of subjects. The subjects are chosen based on their availability or the purpose of the study, and in some cases, on the sole discretion of the researcher.
• Types of Non-Probability Sampling

  • Quota Sampling
  • Voluntary Sampling
  • Purposive or Judgemental Sampling
  • Availability Sampling
  • Snowball Sampling
• Types of Non-Probability Sampling

  Quota Sampling - You resort to quota sampling when you think you know the characteristics of the target population very well. In this case, you tend to choose sample members possessing or indicating the characteristics of the target population.
• Types of Non-Probability Sampling

  Voluntary Sampling - Since the subjects you expect to participate in the sample selection the ones volunteering to constitute the sample, there is no need for you to do any selection process.
• Types of Non-Probability Sampling

  Purposive or Judgemental Sampling - You choose people whom you are sure could correspond to the objectives of your study, like selecting those with rich experience or interest on your study.
• Types of Non-Probability Sampling

  Availability Sampling - The willingness of a person as your subject to interact with you counts a lot in this non-probability sampling method.
• Types of Non-Probability Sampling

  Snowball Sampling - Similar to snow expanding widely or rolling rapidly, this sampling method does not give a specific set of samples. This is true for a study involving unspecified group of people.