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.
Double Barreled Question
A survey question whereby two separate ideas are erroneously presented together in one question.
Double Blind Experiment
A research design where both the experimenter and the subjects are unaware of which is the treatment group and which is the control.
Double-Barreled Question
A double-barreled question asks two questions in one. For example, "Please rate how strongly you agree or disagree with the following statement: 'My child is happy at his/her child care center and the price is right for the type of care'." In the example, respondents are asked to give a single response to two different questions, one about their child's happiness and one about the price of care.
Dummy Coding
A coding strategy where a categorical variable is turned into a series of dichotomous variables (dummy variables) each of which have a value of 0 or 1. Dummy variables are used in regression analysis to measure the effect of a categorical variable on the outcome when the original categorical variable has more than 2 values. For a given categorical variable, k-1 dummy variables are entered into the regression equation, where k is the number of values in the original categorical variable.
Dummy Variables
Categorical variables that are assigned a value of 0 or 1 for use in a statistical analyses (see Dummy Coding).
Duration Models
A group of statistical models used to measure the length of a status or process.