Research in music education
A "survey" is a systematic method of collecting information on one or more variables. An example of a survey study is a 1998 study by Gillespie and Hamann. The purpose of the study was to gather descriptive information about orchestra programs that can be used as baseline data when considering the needs of school string programs. The findings indicated a continued enrollment increase in school orchestras in the 1990s although the number of orchestra teachers remained stable, and that larger schools are more likely to offer orchestra instruction. The impact of the study was the recommendation that school systems should provide larger, more adequate teaching facilities and that universities and string teachers should emphasize strategies for teaching larger string classes in their teacher preparation programs.
Statistics
A common goal for a statistical research project is to investigate causality, and in particular to draw a conclusion on the effect of changes in the values of predictors or independent variables on dependent variables. There are two major types of causal statistical studies: experimental studies and observational studies. In both types of studies, the effect of differences of an independent variable (or variables) on the behavior of the dependent variable are observed. The difference between the two types lies in how the study is actually conducted. Each can be very effective.
An experimental study involves taking measurements of the system under study, manipulating the system, and then taking additional measurements using the same procedure to determine if the manipulation has modified the values of the measurements. In contrast, an observational study does not involve experimental manipulation. Instead, data are gathered and correlations between predictors and response are investigated.
While the tools of data analysis work best on data from randomized studies, they are also applied to other kinds of data—like natural experiments and observational studies—for which a statistician would use a modified, more structured estimation method (e.g., Difference in differences estimation and instrumental variables, among many others) that produce consistent estimators.