POPM 3240 Lecture Notes - Lecture 6: Clinical Trial, Simple Random Sample, Confidence Interval
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Census: the whole population is surveyed (eg. stats canada population census) Sample: a portion of the population is surveyed (eg. 10% of ontario residents are randomly sampled to obtain demographic information) Want to make inferences about the entire population based on this sample. To describe characteristics of a population (eg. descriptive study) To assess specific associations between factors (exposures) and disease (outcome) (eg. analytical study) Logistics (need a list of everyone, need to get a hold of everyone) Main stages to sampling: determine who/what to sample, determine how you"re going to choose these subjects, determine how many you"ll need to be confident in your findings. How you go about choosing your subjects will have an impact on the validity of your results. If your subjects are not truly representative of the population of interest, then your conclusions may be biased (i. e. wrong) You want to be sure that you"re getting a good representation of the population of interest.