Quantitative Reasoning Vocab

Classical test theory

A framework for conceptualizing score reliability that defines a score as being a function of a true score (the average score an individual would get on a measure) and a random error score that moves the true score higher or lower than it would typically be

Concurrent criterion validity

How well a test’s scores correlate with a criterion that exists in the present

Construct-based validity

How well a test score reflects an abstract hard-to-observe concept, such as intelligence or aggression

Content-based validity

A characteristic of items on a test that are a fair representation of the items that could be on the test

Criterion-based validity

A type of validity that examines how well a test correlates with an external criterion that exists in either the present (concurrent) or the future (predictive)

Cronbach’s alpha

A coefficient of reliability that estimates internal consistency among the items on a measure. It generally ranges from .00 to 1.00

Dependent variable

The outcome variable in a research study, or the variable that a researcher believes is affected by some other variable (the independent variable)

Error score

The part of a test score that is random and contributes to the unreliability of a test.

Independent variable

The causal variable in a research study, or the variable that a researcher believes affects some other variable (the dependent variable)

Internal consistency reliability

A type of reliability that reflects how well items on a single test correlate with each other

Interrater reliability

A type of reliability that reflects how well two different human scorers agree

Observed score

The score that an individual gets on a test or measure

Predictive criterion validity

How well a test’s scores correlate with a criterion that will exist in the future

Reliability

the degree to which a test produces stable and consistent results over time

Test–retest reliability

refers to the consistency of test scores when the same test is administered to the same group at two different points in time

True score

The typical score you would get if you took the same test an infinite number of times and averaged all the slightly different scores you would get

Validity

The degree to which scores from a measure represent the abstract concept that a researcher thinks it does

Average

The most representative score in a set of scores

Data

A record of an observation or an event such as a test score, a grade in math class, or response time

Data set

A set of data points

Descriptive statistics

Values that organize and describe the characteristics of a collection of data, sometimes called a data set

Inferential statistics

Tools that are used to infer characteristics of a population based on data from a sample of that population

Mean

A type of average calculated by summing values and dividing that sum by the number of values

Measures of central tendency

The mean, the median, and the mode

Median

The midpoint in a set of values, such that 50% of the cases in a distribution fall below the median and 50% fall above it

Mode

The most frequently occurring score in a distribution

Outliers

Those scores in a distribution that are noticeably much more extreme than the majority of scores. Whether a score is an outlier or not is usually an arbitrary decision made by the researcher

Percentile rank

The percentage of cases equal to and below a particular score in a distribution or set of scores

Population

All the possible subjects or cases of interest

Sample

A subset of a population

Skew

The degree of asymmetry of a distribution indicating more scores on one side than the other

Statistics

Quantitative tools and techniques that are used for describing, organizing, and interpreting information

Alternative hypothesis

Represents one of two possible truths: Either the null hypothesis is more likely, or its alternative, the research hypothesis, is more likely

Directional research hypothesis

A research hypothesis that posits a statistical result that is in a particular direction, such as a positive correlation or a mean difference in favor of a particular group

Hypothesis

A statement of relationship between two or more variables. It is the guessed answer to a research question

Nondirectional research hypothesis

A research hypothesis that posits a relationship among variables but not the direction of the relationship. For instance, it might predict a difference between groups but not which group will score higher

Null hypothesis

A statement of equality between groups or the absence of relationship among variables

Parameter

A value that describes a population

Population

All the possible subjects or cases of interest

Research hypothesis

A statement of relationship among variables

Sample

A subset of a population meant to represent the population