Week 69 (10.8.08)

Learn

Chapter 7 : Selecting samples

For many research questions and objectives, it will be impossible to either collect or to analyse all the data available owing to restrictions of time, money and ofter access.

Sampling techniques provide a range of methods that enable to reduce the amount of data needed to collect by considering only data from a subgroup rather than all possible cases or elements.

Sampling provides a valid alternative to a census when:

• it would be impracticable for you to survey the entire population
• your budget constraints prevent you from surveying the entire population
• your time constraints prevent you from surveying the entire population
• you all collected all the data but need the results quickly

Sampling techniques available can be divided into 2 groups:

• probability or representative sampling - the chance, or probability of each case being selected from the population is known and usually equall for all cases.
• non-probability samples - the probability of each case being selected from the total population is not known and it is impossible to answer research questions or to address objectives that require you to make statistical inferences about the characteristics of the population. You may still be able to generalise from non-probability samples about the population, but not on statistical grounds.

Unlearn

NIL

Relearn

Learning from the above, for my BAP assisgnment, I chose to use non-probability sampling because it can increase the accuracy of the results by not having any influence on the sample population. The questionnaire sent to them does not focus on whom i select but instead base on the convenience of the SEs to provide the information of the survey through "free post".

Unlike intranet survey for probability sampling, respondent may felt bias in responding because of the sensitivity in sending back the results via intranet (researcher know who send back the results of the survey).