AP Psych Unit 1 Part 2-Research Methods, Ethics, and Statistics

hindsight bias

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

Theory

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

operational definition

a carefully worded statement of the exact procedures used in a research study

Replication

repeating the essence of a research study, usually with different participants in different situations, to see whether the basic finding extends to other participants and circumstances

case study

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

naturalistic observation

a descriptive technique of observing and recording behavior in naturally occurring situations without trying to manipulate and control the situation

survey

A study, generally in the form of an interview or questionnaire, that provides researchers with information about how people think and act.

sampling bias

A problem that occurs when a sample is not representative of the population from which it is drawn.

Population

all those in a group being studied, from which samples may be drawn. (Note: Except for national studies, this does not refer to a country's whole population.)

random sample

method of selecting from a population in which each person has an equal probability of being selected

representative sample

A sample that reflects the characteristics of the population from which it is drawn

Correlation

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

correlation coefficient

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

variable

anything that can vary and is feasible and ethical to measure.

Scatterplot

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

illusory correlation

the perception of a relationship where none exists

regression toward the mean

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

experiment

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

experimental group

in an experiment, the group 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.

random assignment

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

double-blind study

An experiment in which neither the participant nor the researcher knows whether the participant has received the treatment or the placebo

Placebo

something which has a positive mental effect, but no physical effect

confounding variable

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

dependent variable

The measurable effect, outcome, or response in which the research is interested.

informed consent

an ethical principle that research participants be told enough to enable them to choose whether they wish to participate

debriefing

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

descriptive statistics

statistics that summarize the data collected in a study

Histogram

A graph of vertical bars representing the frequency distribution of a set of data.

Mode

The value that occurs most frequently in a given data set.

mean

the arithmetic average of a distribution, obtained 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

skewed distribution

When the results are not symmetrical (appears to favor one side over the other)

range

the difference between the highest and lowest scores in a distribution

standard deviation

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

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.

inferential statistics

numerical methods used to determine whether research data support a hypothesis or whether results were due to chance

statistical significance

how likely it is that an obtained result occurred by chance

Hypothesis

A testable prediction, often implied by a theory

independent variable

The experimental factor that is manipulated; the variable whose effect is being studied.

Validity

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