Unit 2: Research Methods: Thinking Critically With Psychological Science

hindsight bias

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

critical thinking

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

theory

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

hypothesis

a testable prediction, often implied by a theory

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

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

survey

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

sampling bias

a flawed sampling process that produces an unrepresentative sample

population

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

random sample

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

correlation

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

correlation coefficient

a statistical index of the relationship between two variables (-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; amount of scatter suggests the strength of the correlation

illusory correlation

the perception of a relationship where none exists

experiment

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

experimental group

in a 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

random assignment

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

double-blind procedure

an experimental procedure in which both the research participants and the research staff are ignorant about whether the research participants have received the treatment or a placebo

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

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 test or experiment measures or predicts what it is supposed to

descriptive 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 the highest and lowest scores in a distribution

standard deviation

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

normal curve

a symmetrical, bell-shaped curve that describes the distribution of many types of data; most scores fall near the mean, 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 postexperimental explanation of a study, including its purpose and any deceptions, to its participants