Psychology: Chapter 1
confounding variable
a factor other than the independent variable that might produce an effect in an experiment
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)
correlation
a measure of the extent to which two factors vary together, and thus of how well either factor predicts the other
experiment
a research method in which an investigator manipulates one or more factors (independent variables) to observe the effects on some behavior or mental process (the dependent variable); by random assignment of participants, the experimenter aims to control other relevant factors
random sample
a sample that fairly represents a population because each member has an equal chance of inclusion
operational definition
a statement of the procedures (operations) used to define research variables ex: human intelligence may be operationally defined as "what an intelligence test measures"
correlation coefficient
a statistical index of the relationship between two things (from -1 to +1)
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
hypothesis
a testable prediction, often implied by a theory
population
all the cases in a group being studied, from which samples may be drawn [note: except for national studies, this does not refer to a country's whole population]
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
case study
an observation technique in which one person is studied in depth in the hope of revealing universal principles
random assignment
assigning participants to experimental and control group by chance, thus minimizing preexisting differences between those assigned to the different groups
confounding variables
by using *random assignment*, researchers are able to control for ___________ which are other factors besides the independent variable(s) that may influence research results
how are correlational research methods conducted?
collect data on two or more variables; no manipulation
double-blind procedure
controls for the placebo effect; neither researchers nor participants know who receives the real treatment
how are descriptive research methods conducted?
do case studies, naturalistic observations, or surveys
what are the weaknesses of the correlational research method?
does not specify cause and effect
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
random assignment
helps minimize preexisting differences between experimental and control groups
random sampling
helps researchers generalize from a small set of survey responses to a larger population
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
how are experimental research methods conducted?
manipulate one or more factors; use random assignment
what are the weaknesses of the descriptive research method?
no control of variables; single cases may be misleading
what is manipulated in the correlational research method?
nothing
what is manipulated in the descriptive research method?
nothing
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
what are the weaknesses of the experimental research method?
sometimes not feasible; results may not generalize to other contexts; not ethical to manipulate certain variables
independent variable
the experimental factor that is manipulated; the variable whose effect is being studied
what is manipulated in the experimental research method?
the independent variable(s)
dependent variable
the outcome factor; the variable that may change in response to manipulations of the independent variable
hindsight bias (I-knew-it-all-along phenomenon)
the tendency to believe, after learning an outcome, the 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
what is the basic purpose of the correlational research method?
to detect naturally occurring relationships; to assess how well one variable predicts another
what is the basic purpose of the experimental research method?
to explore cause and effect
what is the basic purpose of the descriptive research method?
to observe and record behavior
