Research Methods module #4-#8

correlation

A measure of the extent to which two variables change 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

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.

median

Middle number

independent variable

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

dependent variable

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

operational definition

a carefully worded statement of the exact procedures 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

scatterplot

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

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)

statistical significance

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

survey

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

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 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 set 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 those assigned to the different groups

mean

average

placebo 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.

mode

most frequently occurring number

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

range

the difference between the highest and lowest scores in a distribution

culture

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

validity

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

illusory correlation

the perception of a relationship where none exists

debriefing

the postexperimental explanation of a study, including its purpose and any deceptions, to its participants

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.

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, discerns hidden values, evaluates evidence, and assesses conclusions.