ISDS ch 4
Terms
undefined, object
copy deck
- population
- the set of all possible elements that could theoretically be observed or measured; sometimes referred to as the universe
- sample
- a selected portion from the elements within the population, with these elements actually being measured or observed
- census
- the actual measurement or observation of all possible elements form the population; this can be viewed as a "sample" that includes the entire population
- parameter
- characteristic of the population, such as the population mean, standard deviation, or population proportion
- statistic
- characteristic of the sample, such as the sample mean, standard deviation, pr sample proportion. in practice, this is used as an estimate of the (typically unknown) value of the corresponding population parameter
- sampling error
- the error, or difference between the populatin parameter and its corresponding sample statistic, that occurs because a sample has been taken instead of a census. this is a nondirectional, or random error. this type of error is reduced by increasing the size of a probability sample
- nonsampling error
- the error, or difference between the population parameter and its corresponding sample statistic, that occurs because of a directional tendency, or bias, in the measuring process
- simple random sample
- a probability sample in which every person or element in the population has an equal chance of being included in the sample
- systematic sample
- probability sample in which a random starting point between 1 and k is selected, then every kth element in the sample is tested
- stratified sample
- probability sample in which the population is divided into layers, or strata, then a simple random sample of members from each stratum is selected. strata members have the same percentage representation in the sample as they do in the population
- cluster sample
- probability sampling technique in which the population is divided into groups, the members of a random selection of these groups are collected by either a sample or census
- convenience sample
- nonprobability sampling technique where members are chosen primarily because thay are both readily available and willing to participate
- quota sample
- nonprobability sampling technique that is similar to the stratified sample, but where members of the various strata are not chosen through the use of a probability sampling method
- purposive sample
- nonprobability sampling technique where members are chosen specifically because they're not typical of the population
- judgment sample
- nonprobability sampling technique where the researcher believes the members to be representative of the population