(5) Sampling Procedures

• sampling - a formal process of choosing the correct subgroup called a sample from a population to participate in a research study.
• Two kinds of sampling procedures:

  1. Probability sampling technique
  2. Non-probability sampling techniques
• Probability sampling procedures - the random selection of samples from a population.
• probability sampling procedures - each sample/ element from the population has an equal chance of selection under a given sampling technique.
• kinds of probability sampling technique

  1. simple random sampling
  2. stratified sampling simple
  3. cluster random sampling
  4. systematic random sampling
• simple random sampling - the most frequently used type of probability sampling technique. this is characterized by the idea that the chance of selection is the same for every member of the population
• stratified random sampling - also gives an equal chance to all members of the population to be chosen but the population is first divided into strata/groups before selecting the samples.
• cluster sampling - this procedure is usually applied in large-scale studies, geographical spread out of the population is a challenge, and gathering information will be very time-consuming.
• Steps in cluster sampling:

  1. define the population
  2. cluster the population
  3. randomly select clusters
  4. collect data from clusters
• systematic sampling - this procedure is as simple as selecting samples every nth of the chosen population until arriving at a desired total no. of sample size.
• systematic sampling - the selection is based on a predetermined interval. Dividing the population size by the sample size, the interval will be obtained.
• non-probability sampling procedure - may be used when the researcher cannot employ random selection
• kinds of non-probability sampling techniques:

  1. convenience sampling
  2. snowball sampling
  3. purposive sampling
  4. quota sampling
• convenience sampling - a method of selecting samples that are available and are capable of participating in a research study on a current issue
• snowball sampling - a technique where the researchers 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 - also called subjective sampling. It employs a procedure in which samples are chosen for a special purpose.
• quota sampling - gathering a representative sample from a group based on certain characteristics of the population chosen by the researcher.