VariablesIndependent 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 VariableVariations 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 ReliabilityValidity: 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.

ReliabilityReliability 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 InformationPurpose of study Problem statement/research questions Assumptions & limitationsRationale/significance Research methodology - general method, data collection

and analysis Major findings and conclusions

Research EthicsAs 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 BoardsThe 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.