AP Psych: Research Methods (Modules 4-8)

operational definition

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

standard deviation

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

case study

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

confounding variable

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

sampling bias

a flawed sampling process that produces an unrepresentative sample

skewed distribution

a representation of scores that lack symmetry around their average value

experiment

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

statistical significance

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

normal curve/distribution

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

hypothesis

a testable prediction, often implied by a theory

population

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

informed consent

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

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 ser of principles that organizes observations and predicts behaviors or events

random assignment

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

histogram

bar graph depicting a frequency distribution

placebo effecf

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

scatterplot

graphed cluster of dots, each of which represents the values of two variables. The slop of the point 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).

experimental groups

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 not exposed to the treatment; contrasts with the experimental group and serves as a comparison for evaluating the effect of the treatment

correlation

measure of the extent to which two variables change together, and thus how well either variable predicts the other

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

naturalistic observation

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

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

random sample

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

correlation coefficient

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

survey

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

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

culture

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

independent variable

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

validity

the extent to which a test or experiment 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

dependent variable

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

illusory correlation

the perception of a relationship where none exists

debriefing

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

hindsight bias

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

critical thinking

thinking that does not blindly accept arguments and conclusions. Rather, it examines assumptions, assesses the source, discerns hidden values, evaluates evidence, and assesses conclusions.