PHA 335 Variable Types

Independent Variable(s) - IV

• Explanatory variable(s)

• Situation, characteristic, or phenomenon within which the subject functions

  • Those which the INVESTIGATOR can control

    • Examples: medications, educational trainings

  • Those which have already occurred (environmental or personal characteristics)

    • Examples: insurance type, demographic information (e.g., race, gender, socioeconomic status), genetics

Dependent variable(s) (DV)

• Other terms used in literature:

  • End point(s)

  • Outcome variable(s)

• Attempts to measure the effects or results of the treatment of the independent variable(s)

Confounding variable

• A variable that is either unknown or NOT CONTROLLED by the researcher

• Confounding variable can influence either IV, DV, or both

Control variable

• Possible confounding variable that has been taken into account by the investigator.

• Three ways of ”controlling a confounding variable”:

  • Build the control variable into the research design

    • Randomization

    • Restriction

    • Matched pairs

  • Stratify the data analysis (e.g., break into groups)

  • Multiple variable regression analysis