DESCRIBING SAMPLE AND SAMPLING PROCEDURE

• Subjects/participants


  Individuals or entities which serve as the focus of the study
• Respondents


  Individuals or groups of people who actively serve as sources of information during data collection
• Elements


  Members of a population who can provide information for the population
• Population (N)


  The total elements about which you can make inferences based on the data gathered
• Target population


  The entire group of people or objects to which the researcher wishes to generalize the findings of the study
• Accessible population


  A portion of the population to which the researcher has reasonable access
• Sample (n)


  A selection of respondents for a research study to represent the total population (N)
• Factors to Consider in Determining the Sample Size

  • Homogeneity of the population
  • Degree of precision desired by the researcher
  • Types of sampling procedure
• Margin of error (e)


  The allowable error margin in research
• A confidence interval of 95% gives a margin of error of 5%; a 98% confidence interval gives a margin of error of 2%; a 99% confidence interval gives a margin of error of 1%
• Sampling

  The process of selecting and getting the respondents of the study with the minimum cost such that resulting observations will be representative of the entire population
• Purpose of Sampling

  To imitate the behavior of the entire population based on a few observations only
• Sampling Techniques

  • Probability Sampling Procedure
  • Non-Probability Sampling Procedure
• Probability Sampling

  A type of sampling in which all the members of an entire population have a chance of being selected
• Probability Sampling Procedure

  • Simple random sampling
  • Systematic random sampling
  • Stratified random sampling
  • Cluster sampling
  • Multi-stage sampling
• Simple Random Sampling

  The most frequently used type of probability sampling technique where the chance of selection is the same for every member of the population
• the fishbowl method


  1. Prepare sampling frame

  2. Write names on strips of paper

  3. Place in bowl

  4. Draw samples as desired
• Using a table of random numbers

  1. Assign numbers to population elements

  2. Enter table at random starting point

  3. Follow systematic movement to select numbers

  4. Continue until desired sample is reached
• Systematic Random Sampling

  Follows specific steps and procedures in doing the random selection of the samples, where every nth element in the list is drawn for inclusion in the sample
• Stratified Random Sampling


  The population is organized into homogenous subsets before drawing the samples, where the population is divided into sub-populations called strata
• Stratified Random Sampling


  1. Divide population into strata

  2. Apply simple random sampling to each stratum

  3. Determine sample size from each stratum proportionate to population size
• Cluster Sampling


  A technique in which the unit of sampling is not the individual but the naturally occurring group of individuals
• Multi-stage sampling


  A procedure that moves through a series of stages from more inclusive to the less inclusive sampling units until arriving at the population elements that constitute the desired sampling
• Non-Probability Sampling


  A process of selecting respondents in which not all members of the entire population are given a chance of being selected as samples

  also called as non-scientific sampling ( used in qua research mostly)
• Non-Probability Sampling Procedure


  • Convenience sampling
  • Quota sampling
  • Purposive sampling
  • Snowball sampling
• Convenience Sampling


  A method of selecting samples that are available and are capable of participating in a research study on a current issue

  
  

  called as haphazard or availability sampling

  
  

  called as accidental or incidental sampling
• Snowball Sampling


  A technique where the researcher identifies a key informant about a research of interest and then ask that respondent to refer or identify another respondent who can participate in the study
• Purposive Sampling or Judgement Sampling


  A technique where samples are chosen for a special purpose, used when practical considerations prevent the use of probability sampling
• Quota Sampling


  A technique with provision to guarantee the inclusion in the sample of diverse elements in the population and to make sure that these diverse elements are taken into account in proportion in which they occur in the population
• Types of Quota Sampling

  • Proportional quota sampling
  • Non-proportional quota sampling
• Proportional quota sampling


  Sampling that represents the major characteristics of the population by sampling a proportional amount of each
• Non-proportional quota sampling


  Sampling that specifies the minimum number of sampled units in each category, without concern for matching the proportions in the population
• Various Approaches to Determining the Sample Size

  1. Sample sizes as small as 30 are normal curve
  2. sample size- When the total population is equal to or less than 100 (called as universal sampling)
  3. descriptive and comparative research- types of research according to Gay
  4. sample variance s^2 - if the population is normally distributed
  5. slovins formula- lack of knowledge about the behavior of the population
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