AP Psychology: research methods

three main types of research

clinical, experimental, and correlational

independent variable

the manipulated variable in an experiment

dependent variable

what is measured in an experiment

experimental group

the group recieving or reacting to the independent variable in an experiment

control group

the group that does not receive the independent variable in an experiment

random sampling

if a population is too large, a representative sample must be drawn in which every person has an equal chance of being chosen to participate

single-blind

the subjects do not know whether they are in the control group or the experimental group

double-blind

neither the subjects nor the researcher know who is in the control group or the experimental group, but a third party records the data for later analyzation

placebo

a seemingly therapeutic object or procedure that causes the control group to believe they are in the experimental group but actually contains none of the tested material

correlational research

assessing the degree of association between two or more unmanipulated variables or characteristics of interest that occur naturally

clinical research

research in the form of case studies

case studies

intensive psychological studies of a single individual; dangerous because the individual may be atypical of the general population

operational definition

identifies what events are to be studied and demonstrates the process of studying them within the context of an experiment; must be both valid and reliable

counterbalancing

the process of enlisting several groups in an experiment to offset the effects of the test order on the subject

group matching

researchers attempt to categorize the subjects (by age, health status, gender, ect.) and ensure that the control group has members similar to those in the experimental group

naturalistic observation

researchers use to witness and record situations without becoming involved or drawing attention to the study

descriptive statistics

summarize data found from experiments

inferential statistics

allow researchers to test hypotheses about data and to determine how confident they can be in their inferences about the data

central tendency

the typical value in a set of data

mean

arithmetic average of a set of numbers

median

the number that falls exactly in the middle of a distribution of numbers

mode

the most frequently occuring value in the data set

variability

how much numbers in a set differ from one another

standard deviation

measures a function of the average dispersion of numbers around the mean and is a commonly used measure of variability

percentile

expresses the standing of one score relative to all other scores in a set of data

inferential statistics

used to determine our level of confidence that a given set of results would be extremely unlikely to occur if the result was only up to chance

representative

if a sample accurately reflects the characteristics of the population

null hypothesis

states that a treatment had no effect in an experiment

alternative hypothesis

states that a treatment had an effect in an experiment

type 1 error

the conclusion that a difference exists when in fact no such difference does

type 2 error

the conclusion that there is no difference when in fact there is such a difference

informed consent

an agreement to be in a study only after hearing about what types of experiences will be confronted in the study

debriefing

after the conclusion of an experiment, when participants are told the exact purpose of their participation in the research and any deceptive tactics that may have been used

applied psychology

psychology put directly into practice; eg. a therapist meeting with a client

basic psychology

psychology grounded in research