AP Psychology - Unit 0

correlation

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

experiment

A research method in which an investigator manipulates one or more factors to observe the effect on some behavior or mental process

Hypothesis

A testable prediction, often implied by a theory

single-blind procedure

An experimental procedure where participants do not know which experimental condition they have been assigned to, but the experimenter does.

experimenter bias

Bias that occurs when a researcher influences research results in the expected direction.

experimental group

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

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.

histogram

a bar graph depicting a frequency distribution

operational definition

a carefully worded statement of the exact procedures (operations) used in a research study. For example, human intelligence may be operationally defined as what an intelligence test measures.

standard deviation

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

sampling bias

a flawed sampling process that produces an unrepresentative sample

scatterplot

a graphed cluster of dots, each of which represents the values of two variables

case study

a non-experimental technique in which one individual or group is studied in depth in the hope of revealing universal principles

skewed distribution

a representation of scores that lack symmetry around their average value

random sample

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

correlation coefficient

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

meta-analysis

a statistical procedure for analyzing the results of multiple studies to reach an overall conclusion

statistical significance

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

population

all those in a group being studied, from which samples may be drawn

double-blind procedure

an experimental procedure in which both the research participants and the research staff are ignorant (blind) about whether the research participants have received the treatment or a placebo. Commonly used in drug-evaluation studies.

theory

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

variable

anything that can vary and is feasible and ethical to measure

random assignment

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

social desirability bias

bias from people's responding in ways they presume a researcher expects or wishes

self-report bias

bias when people report their behavior inaccurately

effect

experimental results caused by expectations alone; any effect on behavior caused by the administration of an inert substance or condition, which the recipient assumes is an active agent

informed consent

giving potential participants enough information about a study to enable them to choose whether they wish to participate

confounding variable

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

independent variable

in an experiment, the factor that is manipulated; the variable whose effect is being studied

dependent variable

in an experiment, the outcome that is measured; the variable that may change when the independent variable is manipulated

placebo

latin for "I shall please"

survey

non-experimental method; a quasi-experimental method in which questions are asked to subjects; when being designed, the researcher hast o be careful that the questions are not skewed or biased towards a particular answer

naturalistic observation

non-experimental method; research in which subjects are observed in their natural environment

inferential statistics

numerical data that allow one to generalize- to infer from sample data the probability of something being true of a population

descriptive statistics

numerical data used to measure and describe characteristics of groups. Includes measures of central tendency and measures of variation.

illusory correlation

perceiving a relationship where none exists, or perceiving a stronger-than-actual relationship

Quantitative Research

research that collects and reports data primarily in numerical form

Qualitative Research

research that relies on what is seen in field or naturalistic settings more than on statistical data

peer reviewers

scientific experts who evaluate a research article's theory, originality, and accuracy

mean

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

range

the difference between the highest and lowest scores in a distribution

validity

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

median

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

mode

the most frequently occurring score(s) in a distribution

percentile rank

the percentage of scores below a specific score in a distribution of scores

falsifiable

the possibility that a hypothesized relationship can be shown to be incorrect

debriefing

the post-experimental explanation of a study, including its purpose and any deceptions, to its participants

effect size

the strength of a relationship between two or more variables

normal curve

the symmetrical bell-shaped curve that describes the distribution of many physical and psychological attributes. Most scores fall near the average, and fewer and fewer scores lie near the extremes.

regression toward the mean

the tendency for extreme or unusual scores to fall back (regress) toward their average.

hindsight bias

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

critical thinking

thinking that does not automatically accept arguments and conclusions. rather, it examines assumption, appraises the source, discerned hidden biases, evaluates evidence, and assesses conclusions.