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Published byAbel Gaines Modified over 9 years ago
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4.1 CLUSTERS AND CLUSTER SAMPLES By Keaton Kemnitz & Esteban Luis Asencio Otero Garcia de Guantanemo Masson
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CLUSTERS When a population is divided into smaller groups, or clusters, that mirror the characteristics of the population
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CLUSTER SAMPLE To make a cluster sample, divide the population into clusters. Then choose an SRS, or stratified random sample, of the clusters. All individuals in the chosen clusters are included in the sample.
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4.1: WHAT NOT TO DO IN A SURVEY
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BIAS Failure to use random sampling often results in bias Bias are systematic errors in the way a sample represents the population The design of a statistical study shows bias if it systematically favors certain outcomes
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VOLUNTARY RESPONSE SAMPLE A voluntary response sample consists of people who choose themselves by responding to a general appeal. Voluntary response samples show bias because people with strong opinions (often in the same direction) are most likely to respond
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CONVENIENCE SAMPLE Choosing individuals who are easiest to reach results in a convenience sample Convenience samples are prone to large bias due to this fact
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