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Random Sampling

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When is Random Sampling not the best approach to sample selection? Provide an example

A random sample is one in which every member of the population has an equal chance of being selected to be part of the sample. For example, you could obtain a random sample by having everyone in a population roll a die and choosing those people who roll a 6. In contrast, the sample would not be random if you chose everyone taller than 6 feet, because not everyone would have an equal chance of being selected ( Bennett, Briggs, Triola, 2009).
Example: Telephone Book Sampling
If you want to conduct an opinion poll in which the population is all the residents in a town. Could you choose a random sample from selecting names from the local telephone book?
A sample drawn from a telephone book is not a random sample of the town population because phone books are missing a lot of names, and anyone whose name is missing has no chance of being selected. The phone book will be missing names and if two or more people share the same phone number the listing could be under one name. The people who choose to have an unlisted phone number or who only use a cell phone do not have the same chance of being polled as the one whom are listed ( Bennett, Briggs, Triola, 2009)

Bennett, J. O., Briggs, W. L., Triola, M. F., (2009). Statistical Reasoning for everyday life. (3rd ed.). Retrieved from University of Phoenix eBook.

Angela Wilson

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