Given the above definition of population, we can say, that our target sample will be representative as long as individual participants of this sample are typical for the population. One can easily find out that inappropriateness of an unusual sample is a popular discursive subject for nursing papers topics. Nonetheless, when obtaining a representative sample does not appear feasible, an alternative experiment with a random sample could be devised. Random selection requires a completely different approach for generalization. However, as soon as a researcher begins the experiment, it is inevitable to make sure that he or she is free of systematic bias. Thus, a researcher may select participants, unconsciously preferring interesting surnames or some features of their appearance.
The second approach to resolving the problem of representative samples is the alternative that uses so-called opportunity samples. In this case, you are expected to work with volunteers exclusively, simply ignoring randomness or representativeness. Such type of study is popular in universities, where young psychology researchers choose their classmates and coevals as a sample; also, a school psychologist could test schoolchildren on a voluntary basis assigning to them a 4th grade book report. Sure thing, these participants would be nowhere near a representative sample, but at least their eagerness to help might underlie a pilot study with future prospects. Above all, your report should comprise the most comprehensive information about people under observation as well as about conditions of your experiment or survey.