AP Unit 1: Scientific Foundations of Psychology (Myers Unit 2)

Myers Unit 2: Research Methods: Thinking Critically with Psychological Science

Hindsight Bias

the tendency to believe, after learning an outcome, that one would have foreseen it "I knew it all along"

Critical Thinking

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

Theory

A hypothesis that has been tested with a significant amount of data

Hypothesis

A testable prediction, often implied by a theory

Operational Definition

a statement of the procedures used to define research variables

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

an observation technique in which one person 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

the collection of data by having people answer a series of questions

Sampling Bias

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

Population

A group of individuals that belong to the same species and live in the same area

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 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)

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

perceiving a relationship where none exists, or perceiving a stronger-than-actual relationship

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 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.

Random Assignment

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

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. "I shall please effect"

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.

validity

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

reliability

the extent to which a test yields consistent results, as assessed by the consistency of scores on two halves of the test, on alternate forms of the test, or on retesting

Construction validity

measure the theoretical construct or trait it was designed to measure (pt satisfaction)

Predictable Validity

The success with which a test predicts the behavior it is designed to predict; it is assessed by computing the correlation between test scores and the criterion behavior.

Internal validity

the degree to which changes in the dependent variable are due to the manipulation of the independent variable.

External Validity

the extent to which the results of a study can be generalized to other situations and to other people.

Categorical data

Data that consists of names, labels, or other nonnumerical values.

Numerical data

Data that consists of numbers

Descriptive statistics

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

Measure of central tendency

mean, median, mode

mode

the most frequently occurring score(s) in a distribution

mean

average

median

Middle number

Measure of variability

how closely scores bunch up around the central point; a statistic that indicates the spread of distribution

variance

standard deviation squared

range

the difference between the highest and lowest scores in a distribution

dispersion

the pattern of spacing among individuals within the boundaries of the population

Skewed distribution

a representation of scores that lack symmetry around their average value

Standard deviation (population vs. sample)

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

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 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

Z score

a measure of how many standard deviations you are away from the norm (average or mean)

Null hypothesis

a statement or idea that can be falsified, or proved wrong

Skewness

The extent to which cases are clustered more at one or the other end of the distribution of a quantitative variable rather than in a symmetric pattern around its center

Right skew

mean > median

Left skew

mean is less than median

Types of Scales

nominal, ordinal, interval, ratio

Categorical Scale (nominal or ordinal

Quantitative Scale (interval or ration)

regression

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

probability

A number that describes how likely it is that an event will occur

Culture

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

Ethical Principles

Informed consent, Protection from harm/discomfort, Confidentiality, debriefing

Informed Consent

An ethical principle requiring 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