
Operationalization
The process of specifying the operations that will indicate the value of cases on a variable.

Indicator
The question or other operation used to indicate the value of cases on a variable.

Constant
A number that has a fixed value in a given situation; a characteristic or value that does not change.

Measurement
The process of linking abstract concepts to empirical indicants.

Operation
A procedure for identifying or indicating the value of cases on a variable.

ClosedEnded (FixedChoice) Question
A survey quesiton that provides preformatted response choices for the respondent to circle or check.

Mutually Exclusive
A variable's attributes (or values) are mutually exclusive when every case can be calssified as having only one attribute (or value).

OpenEnded Question
A survey question to which the respondent replies in his or her own words, either by writing or by talking.

Unobstrusive Measure
A measurement based on physical traces or other data that are collected without the knowledge or participation of the individuals or groups that generated the data.

Level of Measurement
The mathematical precision with which the values of a variable can be expressed. The nominal level of measurement, which is qualitative, has no mathematical interpretation; the quantitative levels of measurement  ordinal, interval, and ratio  are progressively more precise mathematically.

Nominal Level of Measurement
Variables whose values have no mathematical interpretation; they vary in kind or quality, but not in amount.

Exhaustive
Every case can be classified as having at least one attribute (or value) for the variable.

Ordinal Level of Measurement
A measurement of a variable in which the numbers indicating a variable's values specify only the order of the cases, permitting "greater than" and "less than" distinctions.

Discrete Measure
A measure that classifies cases in distinct categories.

Index
The sum or average of responses to a set of questions about a concept.

Interval Level of Measurement
A measurement of a variablein which the numbers indicating a variable's values represent fixed measurement units but have no absolute, or fixed, zero point.

Ratio Level of Measurement
A measurement of a variable in which the numbers indicating a variable's values represent fixed measuring units and an absolute zero point (zero means absolutely no amount of whatever the variable indicates).


Dichotomy
Variable having only two values.

Idiosyncratic Errors
Errors taht affect a relatively small number of individuals in unique ways that are unlikely to be repeated in just the same way.

Unbalanced Response Choices
A fixedchoice survey question has a different number of positive and negative response choices.

Balanced Response Choices
An equal number of responses to a fixedchoice survey question express positive and negative choices in comparable language.

Face Validity
The type of validity that exists when an inspection of items used to measure a concept suggests that they are appropriate "on their face."

Content Validity
The type of validity that exists when the full range of a concept's meaning is covered by the measure.

Criterion Validity
The type of validity that is established by comparing the scores obtained on the measure of being validated to those obtained with a more direct or already validated measure of the same phenomenon (the criterion).

Concurrent Validity
The type of validity that exists when scores on a measure are closely related to scored on a criterion measured at the same time.

Predictive Validity
The type of validity that exists when a measure predicts scores on a criterion measured in the future.

Construct Validity
The type of validity that is established by showing that a measure is related to other measures as specified in a theory.

Convergent Validity
The type of validity achieved when one measure of a concept is associated with different types of measures of the same concept.

Disciminant Validity
An approach to construct validation; the scores on the measure to be validated are compared to scores on another measure of the same variable and to scores on variables that measure different but related concepts. Discriminant validity is achieved if the measure to be validated is related most strongly to its comparison measure and less so to the measures of other concepts.

Reliability
A measurement procedure yields consistent scores when the phenomenon being measured is not changing.

TestRetest Reliability
A measurement showing that measures of a phenomenon at two points in time are highly correlated, if the phenomenon has not changed, or have changed only as much as the phenomenon itself.

Intrarater (Intraobserver) Reliability
Consistency of ratings by an observer of an unchanging phenomenon at two or more points in time.

Interitem Reliability
An approach that calculates reliability based on the correlation among multiple items used to measure a single concept. Also known as internal consistency.

Cronbach's Alpha
A statistic commonly used to measure interitem reliability.

Reliability Measure
Statistics that summarize the consistency among a set of measures. Cronbach's alpha is the most common measure of the reliability of a set of items included in an index.

AlternateForms Reliability
A procedure for testing the reliability of responses to survey questions in which subjects' answers are compared after the subjects have been asked slightly different versions of the questions or when randomly selected halves of the sample have been adminstered slightly different versions of the questions.

SplitHalf Reliability
Reliability achieved when responses to the same questions by two randomly selected halves of a sample are about the same.

Interobserver Reliability
When similar measurements are obtained by different observers rating the same persons, events, or places.

Concept
A mental image that summarizes a set of similar observations, feelings, or ideas, indicators, and overlapping dimensions.

Conceptualization
The process of specifying what we mean by a term. In deductive research, ceonceptualization helps translate portions of an abstract theory into specific variables that can be used in testable hypotheses. In inductive research, conceptualization is an important part of the process used to make sense of related observations.

