Question | Answer |
population | the entire group of individuals or instances about whom we hope to learn |
sample | a representative subset of a population examined in hope of learning about the population |
sample survey | a study that asks questions of a sample drawn from some population in the hope of learning something about the entire population |
bias | any systematic failure of a sampling method to represent its population is bias |
randomization | best defense against bias is randomization in which each individual is given a fair, random chance of selection |
census | consists of the entire population (sample) |
population parameter | a numerically valued attribute of a model for a population |
statistic, sample statistic | values calculated for sampled data |
representative | the statistics computed from it accurately reflect the corresponding population parameters |
SRS | simple random sample is said to be representative if the statistics computed from it accurately reflect the corresponding population parameters |
sampling frame | a list of individuals from whom the sample is drawn |
sampling variability | the natural tendency of randomly drawn samples to differ from one another |
stratified random sample | sampling design in which the population is divided into several subpopulations, or STRATA, and random samples are then drawn from each stratum |
cluster sample | a design in which entire groups or clusters are chosen at random, usually selected as a matter of convenience, practicality, or cost, each should be representative of the population and should be heterogeneous and similiar |
multistage sample | sampling schemes that combine several sampling methods are called multistage samples |
systematic sample | drawn by selected individuals systematicallly from a sampling frame; when there is no relationship between the order of the sampling frame and the variables of interest, a systematic sample is representative |
pilot | small trial run of a survey to see if questions are clear |
voluntary response bias | bias introduced to a sample when individuals can choose on their own whether or not to participate; always invalid |
convenience sample | consists of the individuals that are conveniently available, not representative because not all people in the population are equally convenient to sample |
undercoverage | sampling scheme that biases the sample in a way that gives a part of the population less representation than it has in the population suffers from undercoverage |
nonresponse bias | bias introduced when a large fraction of those sampled fails to respond |
response bias | anything in a survey design that influences response |