Sampling for Research

Sampling is a process of collecting data, when the population is large for the study. Sampling is research processes of selecting a particular group from a population so that researcher studying the sample and collect the information in a particular group. It is less expensive and takes less time. Sampling may be the only practical method of data collection. (Guire & Pritts, 2007).


Different Methods of Sampling

There are several ways of taking a sample. Several sampling methods may be divided into two methods as probably methods and non-probability methods. These are:

Probability Sampling Methods: In probably sampling, every element in the population has a known. The main reason to use to probability sampling methods is to sample economically. There are four types of probability methods. These are:

Simple Random Sampling: The most basic of the probability sampling methods is the simple random sample. In this method, all participants or elements have an independent chance of being included in the sample. The most common technique for selecting randomly is the lottery and lucky number technique. This method is used to draw a sample from small group in the populations (Bless, Smith & Kagee, 2006).
Stratified Sampling: In this method, population is divided into subgroups such as gender. Firstly researcher identifies the subgroup or strata on the basic of existing information related to the research. The main reason for taking a stratified sample is to have a more efficient sample that provides accurate information.

Cluster Sampling: This method is a combination of simple random sampling and stratified sampling. It is also known as area sampling. A cluster is a unit that contain
a collection of population elements. Cluster sampling selects more than one population element at a time like a street or block of residences. This is useful when the population is spread out geographically.

Multi-stage Area Sampling: It is preferable that cluster are of equal size, otherwise each elements will not have an equal chance of being selected. This method is commonly used in surveys of householders (Gliner & Morgan, 2000).

Non-Probability Methods: In non-probability method, the probability of any particular member of the population being chosen is unknown. These types of methods may be based on judgment rather than probability. There are four types of non-probability methods. These are:
Accidental or Convenience Sampling: The method of convenience sampling is the unsatisfactory form of non-probability sampling. In this method the selection of respondents or elements by accidental. It may be used when the population is high and researcher wants to collect information quickly and economically (Blaikie, 2009).

Quota Sampling: A commonly used non-profitable method is quota sampling. In this method, firstly the population is divided into subgroups like as gender of different age groups. The selection of subgroup depends on the relevance to the research topic.
Judgement or Purposive Sampling: In this method, the researcher selects a sample to specific purpose and sample members required some appropriate judgment characteristics. It is often used to forecast election results.

Snowball Sampling: It is also known as network or reputational sampling. In this method, responded is related to each others. This is also be used to locate natural social networks such as friendship networks. Reduce sample size and costs are advantage of this method (Maxfield & Babbie, 2011).

Selection of Sampling Methods

There are several advantages and disadvantages of each of the sampling methods. Researcher decision is based on specific project or research problem. Selection of sampling methods is based on the accuracy of the information, cost and time period of the survey. The most common criteria for the selection of sampling methods are:


Determine the Objective: Firstly, researcher identity the objectives of the research study or survey. Researcher also identify the budget or time period of the survey. They are providing guideline in the collection of data or information.

Defining population characteristics: Then researcher identifies the populations included in the survey. Analyze each of the populations, groups, geographic areas or subgroups separately and compare them.

Determining the Sample Size: Then researcher is determined the sample frame, sampling unit or target population. Also determine the various resources in used the collection of information.

Performing: Researcher selected sample size and pulled the sample from the entire population of records and it’s time to perform of collect the information (Loughran, 2010).

References:
Blaikie, N. (2009) Designing Social Research. 2nd ed. USA: Polity Press.
Bless, C., Smith, C.H. & Kagee, A. (2006) Fundamentals of social research methods: an African perspective. 4th ed. South Africa: Juta and Company Ltd.
Gliner, J.A. & Morgan, G.A. (2000) Research methods in applied settings: an integrated approach to design and analysis. USA: Routledge.
Guire, S.M. & Pritts, R. (2007) Audio sampling: a practical guide. USA: Focal Press.
Loughran, M. (2010) Auditing for Dummies. USA: Wiley Publishing Inc.
Maxfield, M.G. & Babbie, E.R. (2011) Basics of Research Methods for Criminal Justice and Criminology. 3rd ed. USA: Cengage Learning.