Chapter 7- sampling Flashcards
sampling frame
list of who you are asking/selecting
quota sampling
based on knowledge of the characteristics of the population being sampled: men/women, age,, incomes
non-probability sampling
based on targetting (purposive selection), NOT ALL elements population have chance to be selected, population is unknown, representativeness often problem
convenience sample
non probability, take what you can find (certain location), no control over representativeness
snowball sample
non-probability, ask people+ let them ask their friends etc
purposive sample
non-probability, ask respondents with particular characteristics, usually specific population (fans), researcher decides how useful the sample will be
quota sample
non-probability, set target number of respondents; ask people till you reach target
volunteer sample
non-probability, let people come to u (place advertisement, experiment)
probability sampling
everybody has chance to be selected; if you select sufficient units, you’ll get representative group
simple random sampling
define population (pick names from hat) when working from a list of subjects or a data base
systematic random sampling
define population, think of ‘system’ to select (every 10th person, need to know size population) when working from list of subjects
stratified random sampling
define population, divide in subgroups/strata with same trait (age, income), randomly sample from each subgroup, improves representativeness of a sample
cluster random sampling
define population, divide into clusters->different traits in each sample, mini-representation of whole population, randomly select one or more clusters
multi-stage cluster sampling
several stages (Shanghai -> urban, suburban, rural -> blocks or towns from each district->residential areas randomly selected from each block or town) errors: when there is an error in the first sample, the other samples will have that same error
stratified
population divided into subgroups or strata by researcher, and then samples from each strata (age, men/women), subgroups well represented, but more difficult