Scientific Method & Experimentation

hypothesis

a testable prediction about the results of a study

null hypothesis

a statement that there is no statistical significance between the variables in a study; this is what the researcher tries to statistically disprove

population

the entire group that a researcher is studying

representative sample

a small group which shares characteristics with the population being studied

random sample

a group of subjects to be studied selected with no pattern

random placement

placing subjects into the experiment or control groups with no pattern

operational definition

a procedure for identifying and measuring variables in a study; required for other researchers to replicate the experiment

independent variable

the variable that is manipulated by a researcher in a study; usually expected to have an effect on other variables

dependent variable

the variable that is measured in a study; usually expected to change across groups/trials

confounding variable

any variable that cannot be entirely controlled/eliminated

experimental control

strategies implemented by a researcher to reduce the effect of confounding variables

experimental group

group that is exposed to the independent variable

control group

group that is not exposed to the independent variable

placebo group

group that receives a fake treatment; mostly used in drug trials

single blind study

study in which subjects do not know which group they are in

double blind study

study in which neither the subjects nor the researcher know which group is receiving the treatment; prevents bias in interpreting the data

p-value

a statistical measurement that indicates how likely it is that an observed relationship between variables is due to chance; can never be a negative value; if this value is less than 0.05, reject the null and accept the hypothesis