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| entire set of individuals of interest. |
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| a set of individuals selected from a pop and intended to represent the population |
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| the group defined by the researcher's specific interests. individuals typically share one characteristic. |
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| the extent to which the characteristics of the sample accurately reflect the characteristics of the population |
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| a sample with the same characteristics as the population |
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| a sample with different characteristics from those of the popuation |
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| selection bias or sampling bias |
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| occurs when participants r subjects are selected in a manner that increases the probability of obtaining a biased sample |
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| the enitre population is known, each individual in the population hs a specifiable probability of selection, and sampling occurs by a random process based on the probabilities. |
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| a procedure that produces one outcome from a set of possible outcomes. the outcome must be unpredictable each time, and the process must guarantee that each of the possible outcomes is equally likely to occur. |
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| the pop. is not completely known, individual probabilities cannot be known and the sampling method is based on factors such as common sense or ease, with an effort to maintain representativeness and avoid bias. |
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| observations that a large sample will probably be more representative than a small sample. also, the values are more likely to be similar to the actual values for the population. |
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| sampling with replacement |
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| individuals selected for the sample will be recorded and then returned to the population before the next selection is made. the ensures that the prob. of selection remains constant throughout a series of selections. |
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| sampling without replacement |
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| this method removes each selected individual from the pop. before the next selection is made. although the probability of being selected changes with each selection, this method guarantees that no individual will appear more than once. |
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| sampling without replacement |
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Definition
| this method removes each selected individual from the pop. before the next selection is made. although the probability of being selected changes with each selection, this method guarantees that no individual will appear more than once. |
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| a sample is obtained by selecting everth nth participant from a list containing the total population, after a random start. An easy method for obtaining an essentially random sample, but the selections are not really random or independent. |
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| stratified random sampling |
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| a sample is obtained by dividing the population into subgroups (strata) and then randomly selected equal numbers from each of the subgroups. guarantees that each subgroup will have adequate representation, but the overall sample is usually no representative of the population |
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| proportionate stratified random sampling |
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Definition
| a sample is obtained by subdividing the population into strat ad then randomly selecting from each strata a number of participants that is in proportion to the proportions in the population. guarantees that the composition of the sample will be perfectly representative of the composition of the population, but some stata may have limited representation in the sample. |
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| instead of selecting individuals, a sample is obtained by randomly selecting clusters (preexisting groups) from a list of all the clusters within a pop. An easy method for obtaining a large, relatively random sample, but the selections are not really random or independent. |
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| a sample is obtained by selecting individual participants who are easy to get. an easy method for obtaining a sample, but the sample will probably be biased. |
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| a sample is obtained by identifying subgroups to be included, then establishing quotas for individuals to be selected through convenience from each subgroup. allos a researcher to control the composition of a convenience sample, but the sample is probably biased. |
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