1.3 experiments, placebo, double blind, etc
experiment
a treatment is deliberately imposed on the individual in order to observe a possible change in the response/variable. trying to isolate the treatment/control group
randomization
assign individuals to two treatment groups
block
group of individuals sharing some common features that might affect treatment
control group
group that receives placebo treatement
treatment group
group the receives prescribes treatment
randomized block
individuals are first sorted into blocks that might affect treatment. used to assign each individual in the block to one of the treatments
surveying
means of asking people questions to gather data
observational
measurements of individuals are conducted in a way that doest change the response or variable being measured
double blind
neither individuals in the study nor the researchers know which subjects are receiving treatment
surveying issues
non responses, truthfulness, faulty recall, hidden bias, vague wording, etc
placebo effect
occurs when a subject receives no treatment but (incorrectly) believes he/she is in fact receiving treatment and responds favorably
completely randomized experiment
random process used to assign individuals to one of the treatments
replication
reduces chance that results happened by chance
confounding variable
two variables in which the effects one cannot be distinguished from the effects of the other. may be part of the study or may be outside, lurking variables
lurking variable
variable for which no data has been collected but nevertheless has influenced on other variables in the study
blind study
when patients/individuals do not know if they are in the treatment or control group