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.
Likert Scale
A Likert Scale is a type of rating scale used to measure attitudes, values, or opinions about a subject. Survey respondents are asked to indicate their level of agreement or disagreement with a series of statements. The responses are often scaled and summed to give a composite measure of attitudes or opinions about a topic.
Limited Dependent Variable
A limited dependent variable is a variable with the range of possible values "restricted in some important way." Examples include binary variables that have only two values (e.g., child attends child care or not; child is promoted to next grade or not). Also, variables that can only take on certain values (e.g., discrete variables that have a limited set of categories or continuous variables that can only have positive values such as hours worked or wages earned).
Linear Regression
A statistical technique used to find a linear relationship between one or more (multiple) continuous or categorical predictor (or independent) variables and a continuous outcome (or dependent) variable.
Literature Review
A comprehensive survey of the research literature on a topic. Generally the literature review is presented at the beginning of a research paper and explains how the researcher arrived at his or her research questions.
Local Average Treatment Effect
The local average treatment effect (LATE) is the average effect of a treatment for the group of individuals who complied with the random assignment. That is, it is the estimated effect when those assigned to the treatment group received the treatment and those assigned to the control group did not.
Log-Linear Analysis
A technique used in statistics to examine the relationship between two or more categorical variables. The technique is used to test whether the variables are independent of one another or associated in some way. For example, a log-linear model might be used to test whether there is an association between children being 'red shirted' (children whose parents hold them back from entering kindergarten even though they meet the age eligibility requirement for kindergarten entry) and their sex (boys versus girls) and race/ethnicity (African American, Hispanic, White, Asian). The model would test for both main effects and interaction effects.
Logistic Regression
Logistic regression (or logit regression) is a special form of regression used to analyze the relationship between predictor variables and a dichotomous outcome variable. A dichotomous variable is a variable with only two possible values, e.g. child attends center-based child care (Yes/No). For example, a researcher might use logistic regression to study the relationships between parental education, household income, and parental employment and whether children receives child care from someone other than their parents (receives nonparent care/does not receive nonparent care).
Logit Model
A special form of regression used to analyze the relationship between predictor variables and a categorical outcome variable.
Main Effect
The effect of a predictor (or independent) variable on an outcome (or dependent) variable.
MANOVA (Multivariate Analysis of Variance)
MANOVA is an extension of analysis of variance (ANOVA). ANOVA is used to examine whether there are statistical differences in the group means for a single continuous dependent variable. MANOVA is used when there are two or more dependent variables (outcome variables). It is a statistical test that measures group differences on several dependent variables.