MAT 221 Lecture Notes - Lecture 4: Statistical Inference, Sampling Distribution, Simple Random Sample
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MAT 221 Full Course Notes
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Convenience sampling: just ask whoever is around: bias: opinions limited to individual"s present. Voluntary response sampling: individuals decide for themselves they want to be involved. Often called public opinion polls these are not considered valid or scientific: bias: sample design systematically favors a particular outcome because different people are motivated to respond or not. Ex: in a response: 70% of (10,000) parents wrote to ann landers (an advice columnist) to say that having kids was not worth it if they had to do it over again, they wouldn"t. Simple random sample (srs): is made of randomly selected individuals. Each individual in the population has the same probability of being in the sample: not bias: best sampling method. Stratified random sample: is essentially a series of srss performed on subgroups of a given population. The subgroups are chosen to contain all the individuals with a certain characteristic. (the srs take within each group need not be of the same size)
