AP Psych Unit 2 Vocab

theory

an explanation using an integrated set of principles that organizes and predicts observations

• an idea or set of ideas that is intended to explain facts or events

• scientifically tested and proven

• based on a wide range of data

hypothesis

a testable prediction

• proposed explanation for some phenomenon based on limited evidence

• not scientifically tested or proven

• based on limited data

operational definition

a statement of the procedures used to define research variables; how you intend to measure the dependent variable

ex: intelligence: IQ test

control group

in an experiment, the group that is not exposed to the treatment; contrasts with the experimental group and serves as a comparison for evaluating the effect of the treatment

• does not receive the independent variable

experimental group

in an experiment, the group that is exposed to the treatment, that is, to one version of the independent variable

• does receive the independent variable

independent variable

the experimental factor that is manipulated--the variable whose effect is being studied

dependent variable

the outcome factor -- the variable that is measured and may change in response to manipulations of the independent variable

confounding variable

a factor other than the independent variable that might produce an effect in an experiment that influences the dependent variable

ex: mold on a blueberry

case study

an observation technique in which one person is studied in depth in the hope of revealing universal principles

• investigates one individual or group of individuals

• welcomes data collected through any and all methods

naturalistic observation

observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation

survey

a technique for ascertaining the self-reported attitudes or behaviors of people, usually by questioning a representative, random sample of them

cross sectional study vs. longitudinal study

one method compares two groups at one specific period in time

the other method follows the same person or group of people (often referred to as a cohort) over a period of weeks, months, or even years, testing people at the beginning, end, and various points in between.

hindsight bias

the tendency to believe, after learning an outcome, that you knew that all along

subjective self report

a method where individuals describe their own internal experiences, feelings, and thoughts

• overreliant on self-perception, inaccurate self reports, and subjective and biased

demand characteristics

cues that might indicate the aim of the study to participants

• can lead participants to change their behaviors or responses based on what they think the research is about

• problematic because they can bias research findings

sampling bias

occurs when sample is not random or representative. validity of experiment results is compromised.

population vs. sample

one refers to the entire group of individuals or objects that are the focus of a study

another is a subset of the other that is selected for observation and analysis

random sample

a sample that fairly represents a population because each member has an equal chance of inclusion

representative sample

a subset of a larger population that accurately reflects the characteristics of the whole population

• like a mini-version of the population, with the same proportions and distributions of key features

random assignment

assigning participants to experimental and control conditions by chance ,thus minimizing preexisting differences between those assigned to the different groups

correlation (pos and neg)

a measure of the extent to which two factors vary together, and thus of how well either factor predicts the other

• positive means that two variables operate in unison so that when one variable rises or falls, the other does the same.

• negative means that two variables move opposite one another so that when one variable rises, the other falls.

causation

one event or variable (the cause) leads to a change in another event or variable (the effect

correlation coefficient

a statistical index of the relationship between two things (from -1 to +1)

illusory correlation

the perception of a relationship where none exists

reliability

the consistency of a measurement or test

• how likely are the results reproducible if the test is administered again under similar conditions?

validity

the extent to which a test or experiment measures or predicts what it is supposed to

internal validity vs. external validity

one focuses on whether a study’s results accurately reflects the casual relationship between variables within the study itself

the other assesses the extent to which those findings can be generalized to other populations, settings, and situations

content validity

extent to which a test or measurement covers all relevant parts of the construct it aims to measure

single vs. double-blind procedure

one method has participants unaware which study group they are in

• the staff directly interacting with the participants are aware of the group assignments

the other has both the participants and the staff unaware of the study groups

• this one reduces bias by preventing the staff’s knowledge from influencing their interactions with the participants or the interpretation of the results

placebo effect

any effect that seems to be a consequence of administering a sugar pill

mode

The most frequently occurring score(s) in a distribution

mean

the arithmetic average of a distribution, obtaining by adding the scores and then dividing by the number of scores

median

the middle score in a distribution--half the scores are above it and half are below it

range

the difference between the highest and lowest scores in a distribution

standard deviation

a computed measure of how much scores vary around the mean score

skewed distribution

a statistical term that describes the shape of a set of data in which the values are not evenly distributed around the mean

normal curve

a symmetrical, bell-shaped curve that describes the distribution of many types of data; most scores fall near the mean (68% fall within one standard deviation of it) and fewer near the extremes

statistical significance

a statistical statement of how likely it is that an obtained result occurred by chance

Z score (standard score)

a statistical measure that quantifies how many standard deviations a data point is away from the mean (average) of a dataset