AP PSYCH Statistical Concepts

researcher bias (experimenter bias)- a tendency for researchers to engage in behaviors and selectively notice evidence that supports their hypotheses or expectations

case study- examines one individual in depth in hopes of revealing things true of us all

correlation coefficient- a statistical index of the relationship between two things

experiment- a research method in which an investigator manipulates one or more factors to observe their effect on some behavior or mental process

Institutional Review Board- Group that reviews research in advance to ensure ethical considerations are met

stratified sample- With stratified sampling, the researcher divides the population into separate groups, called strata. Then, a probability sample (often a simple random sample ) is drawn from each group.

operational definition- a statement of the procedures used to measure or manipulate a research variable.

reliability- a measure of consistency

validity- a measurement that refers to the extent to which any tool measures what it is intended or claims to quantify

participant bias (demand characteristics)- a tendency for research participants to respond in a certain way because they know they are being observed, or they believe they know what the researcher wants

survey method- research technique in which information is gathered from people

wording effect- the effect that question phrasing and order have on how people answer surveys

random sample- a sample that fairly represents a population because each member has an equal change of inclusion

cross-sectional study- technique that compares individuals from different age groups at one time

scatterplots- a graphed cluster of dots which represents the values of two variables

illusory correlation- the idea of a relationship where none exists

control group- the group that does not receive the treatment

double blind procedure- an experimental procedure in which both the research participants and the research staff are ignorant to the expected outcome of an experiment

placebo- a non-active substance or condition that may be administered instead of a drug or active agent to see if the drug has an effect beyond the expectations produced by taking it

extraneous variable- a factor other than the independent variable that might produce an effect in the experiment.

statistics- tools that help us see and interpret things we may otherwise miss

range- the gap between the lowest and highest score

skewed- a distribution with its peak well to one side (positive - tail to the right, negative - tail to the left)

risk- the chance that an accident might occur during a research project

scientific method- a method of investigation involving observation and theory to test scientific hypotheses

hindsight bias- the tendency to believe, after learning an outcome, that one would have foreseen it

overconfidence- we tend to think we know more than we do

theory- an explanation using an integrated set of principles that organizes observations and predicts behaviors or events

hypothesis- a testable prediction

replication- repeating a research study or experiment

observation- the simplest scientific technique

dependent variable (DV)- the research variable that is influenced by the independent variable, and the impact can be measured

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

informed consent- participants must be informed about the research and any potential risks involved

population- the group being studied, from which samples may be drawn

naturalistic observation- observing and recording behavior in naturally occurring situations without trying to control the situation

longitudinal study- technique that studies the same group of individuals over a long period of time

confirmation bias- a tendency to search for information that confirms one's preconceptions

experimental group- the group that receives the treatment

random assignment- assigning participants to experimental and control groups by chance

placebo effect- experimental results caused by expectations alone

independent variable (IV)- the variable that a researcher actively manipulates, and if the hypothesis is correct, will cause a change in the dependent variable

confounding variables- a variable that varies systematically with the independent variable; makes interpretation of the cause difficult or impossible.

central tendency- a single score that represents a whole set of numbers

mean- the sum of all the scores divided by the number of scores

median- the middle number in a set of numbers that are listed in order

mode- the most frequently occurring score

standard deviation- a measure of variability that describes an average distance of every score from the mean

normal distribution- describes a symmetrical, bell shaped curve that shows the distribution of many physical and psychological attributes

coercion- making someone do something; not allowed according to ethical guidelines of research

confidentiality- researchers must not release data or information about individual participants

debriefing- participants must receive a full explanation of the research when their involvement is done

Hawthorne effect- (aka observer effect) process where human subjects in an experiment change their behavior simply due to being observed