Sunday, 30 July 2017

Voluntary Sampling Method combined with Social Media Advertising

Dr M H B Ariyaratne
MBBS, MSc(Biomedical Informatics)
Trainee in MD(Health Informatics) at Postgraduate Institute of Medicine, University of Colombo, Sri Lanka

In statistics, we have two main categories of Sampling Methods, Probability Sampling and Non-Probability Sampling.

A voluntary sampling is one of the main types of non-probability sampling methods. A voluntary sample is made up of people who self-select into the survey. Often, these folks have a strong interest in the main topic of the survey.

One of the most recent advancements in information and communication technology to interact with a "population" is Web-2.0. It allows internet users to interact and collaborate with each other in a social media context.

In a research, I want to identify the models of different patterns of prescription writing. My reference population is clinicians across the world. I need to use a convenient sampling method. I have created a self-administered questionnaire to collect data for the research. I create a google form to match the questionnaire. The answers will be collected in a google sheet.

I am combining the voluntary sampling method with the Web-2.0 technology to select my sample by utilizing that opportunities of Web-2.0 to reach out to a global study population.

I thought to advertise on social media sites like FaceBook to fill my questionnaire. I will include a message in the advertisement like "if you are a clinician involved in making prescriptions, please spend three minutes to answer eight simple questions for my research.". Those who volunteer to answer questions will be included in the sample population.

The advantages include that I can reach a very large population which is mainly limited by the cost of advertising. The site like Facebook allows us to select the target population for the advertisement depending on characters like geography, age, sex, occupation and interests. The data entered through the questionnaire is immediately available for analysis. There is no need to enter data as in a paper based questionnaires.

The disadvantages include that the sample may not represent the study population. For example, even though I have advertised it for clinicians, a non-clinician may enter data to the google form.

This method of sampling may be identified as "WEB-2.0 SAMPLING" or "SOCIAL MEDIA SAMPLING".

I have defined this as below.

''SOCIAL MEDIA SAMPLING'' or ''WEB-2.0 SAMPLING'' is a sub type of voluntary sampling where sample population is made up of people who self-select into the survey. Its sample is drawn from voluntary responders to advertisements on Social Media Sites. This method is suitable for a research which can be done through filling a questionnaire.The target population for advertisements can be selected by characteristics like demography, age, gender, income, occupation, education level or interests using advertising tools provided by the social media sites. The advertisement may include a message about the research and will link to a web survey. After voluntary following the link and submitting the web based questionnaire, the respondent will be included in the sample population. This method can reach a global population and limited by the advertisement budget. This method may permit volunteers outside the reference population to volunteer and get included in the sample. It is difficult to make generalizations about the total population from this sample because it would not be representative enough. 

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