The research glossary defines terms used in conducting social science and policy research, for example those describing methods, measurements, statistical procedures, and other aspects of research; the child care glossary defines terms used to describe aspects of child care and early education practice and policy.
Rating Scale
A rating scale is a measuring instrument for which judgments are made in order to rate a subject or case at a specified scale level with respect to an identified characteristic or characteristics.
Ratio
A ratio is a relationship between the number in two groups of objects. It tells us how many times the number in the first group contains the number in the second group. For example, if we have a 10 elementary schools and 3 middle schools in a community, the ratio of elementary to middle schools is 10 to 3 (10:3), or roughly 3 elementary schools to every 1 middle school.
Ratio Scale
A scale in which the difference between the values on the scale are equivalent and the scale has a fixed zero point; values on the scale can be meaningfully measured against each other.
Raw Score
A score obtained from a test, assessment, observation, or survey that has not been converted to another type of score such as a standard score, percentile, ranking, or grade. Although a raw score often provides little useful information, there are exceptions. For example, if all children in a classroom are administered the exact same 20 items on a math test, the raw score is a measure of each child's absolute performance on the test and can be used to compare the math performance of the children in the class.
Refusal Rate
The proportion of all potentially eligible cases (subjects) in a sample that refuses to do an interview, survey, or to provide other requested data (for example, child record data).
Regression Analysis
A statistical technique that measures the relationship between a dependent (outcome) variable and one or more independent (predictor) variables (see linear, logistic and multiple regression).
Regression Coefficient
A coefficient that is calculated for each independent (predictor) variable. The regression coefficient indicates how much the dependent (outcome) variable will change, on average, with each unit change in the independent variables.
Regression Discontinuity Design
A regression discontinuity design (RDD) is a quasi-experimental design that provides unbiased estimates of the treatment effect (effect of an intervention). Participants are assigned to the treatment and control groups based on their score on an assignment variable (e.g., scores of a standardized assessment) that identifies the need for the intervention. Participants below a predetermined cut-point on the assignment variable are assigned to the treatment group (receive intervention) and those at or above the cut-point are assigned to the control group (do not receive intervention). The effect of the treatment is determined by comparing scores on the outcome variable(s) for participants in the two groups who are at or near the cut-point.
Regression Equation
A mathematical equation that indicates the relationship between a dependent (outcome) variable and one or more independent (predictor) variables. The equation indicates the extent to which the dependent variables can be predicted by knowing the value of the independent variables.
Reliability
Reliability is the degree to which an assessment or other measurement tool produces stable and consistent results. Reliability indicates the degree to which a measure will provide the same result for the same person, across similar groups, and irrespective of who administers the assessment or collects the data. A reliable measure will always give the same result on different occasions, assuming that what is being measured has not changed during the intervening period.