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