Discussion Question
Suppose you drew a random sample of all licensed clinical psychologists in your community to interview by phone. On the days you made the phone calls, some of the psychologists were not available to be interviewed, so you drew replacements for them at random from the population of licensed clinical psychologists. Speculate on whether the sample is “biased” or “unbiased” in light of the fact that replacements were drawn at random.
 

Response
From my perspective, I would have to say my response is ‘it depends’.  It is given in the discussion question that the initial random sample was to be drawn from psychologists in the local community.  This leads me to believe that the study my be being conducted to answer a question dealing on a local level rather than a expanded area.  While it is true that drawing a random sample of licensed clinical psychologists from a general pool is conducive to ‘simple random sampling’ (hence unbiased), drawing a random sample from the population of licensed clinical psychologists to make up for the lack of local responses suggest a ‘sample of convenience’, which, of coarse, will lead to biased responses. The responses from these psychologists may or may not be in the interest of the community being studied.
If this study is more generalized, then the fact that the sample from the pool of psychologists is random, the responses should be unbiased.   Without additional information on what is being researched, it is hard to say whether or not this outside sample will be biased or unbiased.  I can only say, in my opinion, that, because of the way the discussion question was presented, I do not believe that this is a study outside of the local community.  Any responses from the ‘sample of convenience’ would, therefore, present the possibility of biased responses.  My assumption could be incorrect, in which case I reassert my answer of ‘it depends’.