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.
Standardization
A scale transformation procedure that involves manipulating data from different types of scales so that they can then be compared. It consists of subtracting the sample mean for the scale from each score on the scale and dividing by the scale's standard deviation.
Standardized Test
A standardized test is a test that is administered, scored, and interpreted in the same way for all test-takers. Scores on standardized test are often, but not always, created so that an individual's test score or the mean of a group's test scores can be compared to the mean of the population of individuals of the same age or grade. The Peabody Picture Vocabulary Test (PPVT) and the Woodcock-Johnson III Tests of Achievement are examples of commonly used standardized tests in early childhood research.
Standardized Variables
The values of variables from different types of scales are transformed so that they can be compared with one another.
Standardized, Open-Ended Interview
A standardized, open-ended interview is a type of qualitative interview that is similar in many ways to a survey. Questions are carefully scripted and written prior to the interview. The researcher asks a uniform series of questions in the same order to each interviewee. The questions are open-ended to capture more details and individual differences in responses.
Statistic
A measure of the characteristics of a sample (e.g., the mean is a statistic that measures the average of a sample). It gives an estimate of the same value for the population from which the sample was selected.
Statistical Analysis
Statistical analysis is the process of collecting, examining, manipulating, summarizing and interpreting quantitative or numerical data for the purpose of identifying patterns, trends, and relationships in the data. It can include the use of descriptive statistics such as percentages, means, variances and correlations and/or the use of inferential statistics such as t-tests, chi-square tests, regression, and analysis of variance (ANOVA).
Statistical Control
Statistical control refers to the technique of removing the effect of one independent variable or set of variables from the effects of the remaining variables on the dependent variable in a multivariate analysis. In statistical analyses with multiple independent variables and a single dependent or outcome variable, the effects of all other variables are held constant or their impact is removed to better analyze the relationship between the outcome variable and each of the independent variables. For example, if one was using multiple regression to examine the relationships between parental education, family income, and employment on parental choices for child care, the effects of income and education would be controlled when estimating the relationship between parent employment and child care choice.
Statistical Inference
Statistical inference is the process of drawing conclusions about or inferring the properties of a population based on analysis of data from a sample of that population.
Statistical Significance
Statistical significance refers to the probability or likelihood that the difference between groups or the relationship between variables observed in statistical analyses is not due to random chance. If there is a very small probability that an observed difference or relationship is due to chance (e.g., p .05), the results are said to reach statistical significance. This means that the researcher concludes that there is a real difference between two groups or a real relationship between the observed variables. See Significance Level for additional information.
Stratification
Grouping the study population into subgroups by their homogenous characteristics before sampling so as to improve the representativeness of a sample.