A university teacher conducts research study where lecture-cum demonstration…

In experimental and quasi-experimental research design, variables are classified by their role. The independent variable (IV) is the variable the researcher deliberately introduces, manipulates, or varies as the treatment or intervention, in order to study the effect it produces. The dependent variable (DV) is the outcome that is measured for change as a result of that treatment. A characteristic that already exists as a fixed attribute of the subjects, and is not manipulated by the researcher, functions instead as a moderator or control variable used only to classify or stratify the sample.

In this study, the university teacher deliberately applies the lecture-cum-demonstration method as the instructional treatment — this is the variable being manipulated. Its effect is observed on students' level of participation, the outcome that is measured, making that the dependent variable. The study further examines this effect in terms of the students' family SES and habitat, but these are pre-existing background characteristics of the subjects that the teacher does not introduce or vary; they serve only as moderator variables for analysing the sample.

• Students' level of participation is the outcome measured after the treatment is applied, which makes it the dependent variable, not the independent one.

• SES of the family is a pre-existing characteristic used to group students for analysis; the teacher does not manipulate it, so it is not the independent variable.

• Habitat of the family is likewise a fixed background attribute of the student's household that exists prior to and independent of the study, not a variable the researcher varies.

So the lecture-cum demonstration method — the treatment the teacher deliberately applies — is the independent variable in this study.