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.