Chapter 2 - Keywords

empiricism

the conviction that accurate knowledge of the world can be acquired by observing it

scientific method

a procedure for using empirical evidence to establish facts

theories

explanations of natural phenomena

hypothesis

a falsifiable prediction made by a theory

empirical method

a set of rules and techniques for observation

operational definition

a description of a property in measurable terms

construct validity

a feature of operational definitions whose specified operations are generally considered good indicators of the specified properties

power

a detector’s ability to detect the presence of differences or changes in the magnitude of a property

reliablity

a detector’s ability to detect the absence of differences or changes in the magnitude of a property

demand characteristics

those aspects of an observational setting that cause people to behave as they think someone else wants or expects

naturalistic observation

a technique for gathering information by unobtrusively observing people in their natural environments

observer bias

the tendency for observers’ expectations to influence both what they believe they observed and what they actually observed

double-blind study

a study in which neither the researcher nor the participant knows how the participants are expected to behave

population

a complete collection of people

sample

a partial collection of people drawn from a population

frequency distribution

a graphic representation showing the number of times that the measurement of a property takes on each of its possible values

normal distribution

a mathematically defined distribution in which the frequency of measurements is highest in the middle and decreases symmetrically in both directions

mode

the value of the most frequently observed measurement

standard deviation

how each of the measurements in a frequency distribution differs from the mean

variables

properties that can have more than one value

correlation

a relationship between variables in which variations in the value of one variable are synchronized with variations in the value of the other

correlation coefficient, r

a mathematical measure of both the direction and strength of a correlation

natural correlation

a correlation that is observed in the natural world

third-variable problem

the natural correlation between two variables cannot be taken as evidence of a causal relationship between them because a third variable might be causing them both

experimentation

a technique for establishing the causal relationship between variables

manipulation

a technique for determining the causal power of a variable by actively changing its value

independent variable

the variable that is manipulated in an experiment

dependent variable

the variable that is measure in an experiment

self-selection

a problem that occurs when anything about a participant determines the value of the independent variable to which the participant was exposed

random assignment

a procedure that assigns participants to conditions by chance

internal validity

an attribute of an experiment that allows it to establish casual relationship

external validity

an attribute of an experiment in which variables have been operationally defined in a representative way

case method

a procedure for gathering scientific information by studying a single individual

random sampling

a technique for selecting participants that ensure that every member of a population has an equal chance of being included in the sample

replication

an experiment that uses the same procedures as a previous experiment but with a new sample from the same population

type 1 error

when researchers conclude that there is a causal relationship between two variables when in fact there is not

type 2 error

when researchers conclude that there is not a causal relationship between two variables when in fact there is

informed consent

a verbal agreement to participate in a study made by an adult who has been informed of all the risks that participation may entail

debreifing

a verbal description of the true nature and purpose of a study