chapter 4 - sampling

desired group to be understood

choosing a group from the population so that ever individual and every group of individuals if likely to be chosen

split the population into groups (strata) that are the same (homogeneous) and take an SRS/simple random sample from each strata

choose a random starting point and use equal intervals to move to every next individual until you have as many as you need

split the groups into groups that are heterogeneous (different) then randomly select the groups themselves and sample everyone in those selected groups

when some members of a population cannot or are less likely to be included in a sample (calling landlines)

when an individual is part of a sample/survey but chooses not to respond or cannot be reached; different from voluntary because people cannot be put into a sample and not respond

patterns of inaccurate results (wording, interviewer, lying, etc.)

no treatment, can't show causation

treatment imposed, shows causation

what is done/not done to the experimental units

used to provide baseline data for comparison

researchers/subjects are unaware of what the treatment given

when only the subjects are unaware of the treatment being given

when a fake treatment works/gives wanted results

2 or more treatments

taking samples and randomly placing in needed groups

keeps all other variables besides treatments constant

using enough exp. units to distinguish differences

groups of experimental units which are similar

separate subjects into block and then randomly assign treatments within each block

this is a block design of pairs where subjects are randomly paired and each individually assigned treatments, and is repeated and given treatment in a random treatment

results are too unusual to have occurred purely by chance, must be < 5% to be so