27 terms

# statistics ch.1

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Descriptive statistics
organize, summarize, and communicate a group of numerical observations
Inferential statistics
use sample data to make general estimates about the larger population
Sample
a set of observations drawn from the population of interest that, it is hoped, share the same characteristics as the population of interest
Population
includes all possible observations about which we'd like to know something
Variable
is any observation of a physical, attitudinal, or behavioral characteristic that can take on different values
Construct
is a hypothetical idea that is developed (or constructed) to describe and explain human behavior
Discrete observations
can take on only specific values (whole numbers); no other values can exist between these numbers
Continuous observations
can take on a full range of values (numbers out to many decimal points); there is an infinite number of potential values
Nominal variable
is a variable used for observations that have categories, or names, as their values
Ordinal variable
is a variable used for observations that have rankings (1st, 2nd, 3rd...) as their values
Interval variable
is a variable that has numbers as its values; the distance (or interval) between pairs of consecutive numbers is assumed to be equal
Ratio variable
is a variable that meets the criteria for interval variables but also has a meaningful zero point
Level
is a discrete value or condition that a variable can take on
Independent variable
is a variable that we either manipulate or observe to determine its effects on the dependent variable
Dependent variable
is the outcome variable that we hypothesize to be related to, or caused by, changes in the independent variable
Confounding variable
is any variable that systematically co-varies with the independent variable so that we cannot logically determine which variable is at work; also called confound
Extraneous variable
is a randomly distributed influence that detracts from the experimenter's efforts to measure what was intended to be measured
Noise
influences an experiment by making the relations between variables less clear than they really are
Reliability
refers to the consistency of a measure
Validity
refers to the extent to which a test actually measures what it was intended to measure
Test-retest reliability
refers to whether the scale being used provides consistent information every time the test is taken
Predictive validity
refers to how well a measuring instrument (such as a personality scale) predicts actual behavior
Hypothesis testing
is the process of drawing conclusions about whether a particular relation between variables is supported by the evidence
Operational definition
specifies the operations or procedures used to measure or manipulate a variable
Experiment
is a study in which participants are randomly assigned to a condition or level or one or more independent variables
Random assignment
every participant is a study has an equal chance of being assigned to any of the groups, or experimental conditions, in the study
Single-blind experiment
is one in which participants do not know the condition to which they have been assigned. This reduces the possibility that participants will respond as they believe they are expected to respond to a given situation