AP Psychology, methods of research

three main types of research
clinical, experimental, and correlational
experiment
an investigation seeking to understand relations of cause and effect
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
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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 design
the subjects do not know whether they are in the control group or the experimental group
double-blind design
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