Variables Independent Variable An independent variable is one that an investigator manipulates to determine its effect. Independent variables seem to have a causative effect upon other variables. Dependent Variable Variations in dependent variables are assumed to depend on or be caused by another variable.

Dependent or Independent? Using the Coke versus Pepsi experiment in the way it was intended to be conducted, what was the dependent variable and what was the independent variable? If the temperature of the drink really determined the outcome, what type of variable would temperature be in the study?

Levels of Measurement of Variables Nominal This level is good for identifying categories. Ordinal In this level categories have an order and this order is significant, common with rankings. Interval At this level variables are ranked using numbers and the distances between the numbers have a real meaning. Ratio In this level an interval variable has a meaningful zero point.

Validity Versus Reliability Validity: Are you measuring what you are supposed to be measuring? Reliability: Are you measuring consistently?

Internal Validity Internal validity is the extent to which observed differences on the dependent variable are attributed to the independent variable and not to some confounding variables. The key to internal validity is whether or not subjects can be randomly assigned to various levels of the independent variable.

External Validity External validity is the extent to which the results of the study can be generalized elsewhere. You make generalizations about a population, is the sample representative of the population?

Content Validity Content validity is the degree to which a test measures an intended content area.

Reliability Reliability is the degree to which a test consistently measures whatever it measures. This is the group to which the researcher would like the sample results of a study to be generalizable.

Sample A sample is a number of individuals selected from a population for a study, preferably in such a way that they represent the larger group from which they were selected.

Research Study Information Purpose of study Problem statement/research questions Assumptions & limitations Rationale/significance Research methodology - general method, data collection and analysis Major findings and conclusions

Research Ethics As a researcher, you have certain ethics you need to uphold. Some of your responsibilities include protecting participants from harm, adhering to promises made to participants, etc.

The Institutional Review Boards The Institutional Review Board at an institution engaged in research must review and approve research if it involves use of human subjects. The Institutional Review Board for the Protection of the Human Subjects (IRB) is the regulatory body of IUP that is responsible for the review of research that involves human participants.