Module 6-8 Psych Vocab

correlation

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

correlation coefficient

a statistical index of the relationship between two variables (from -1.0 to +1.0)

Scatterplot

a graphed cluster of dots, each of which represents the values of two variables. the slope of the points suggests the direction of the relationship between the two variables. the amount of scatter suggests the strength of the correlation (little scatter indicates high correlation)

illusory correlation

the perception of the relationship where none exists

experiment

A research method in which an investigator manipulates one or more factors (independent variables) to observe the effect on some behavior or mental process (the dependent variable). By random assignment of participants, the experimenter aims to control other relevant variables.

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.

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.

placebo

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

independent variable

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

confounding variable

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

dependent variable

The outcome factor; the variable that may change in response to manipulations of the independent variable.

Validity

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

desciptive statistics

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

Histogram

a bar graph depicting a frequency distribution

mode

the most frequently occurring score(s) in a distribution

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

a representation of scores that lack symmetry around their average value

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

normal curve (normal distribution)

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

inferential statistics

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

statistical significance

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

culture

the enduring behaviors, ideas, attitudes, values, and traditions shared by a group of people and transmitted from one generation to the next

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