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