Full Answer Section

• Dependent Variable: This is the variable that the researcher measures to see if it is influenced by the independent variable. It’s the presumed “effect” in a cause-and-effect relationship.
  • Example: In the medication study, blood pressure readings are the dependent variable, as they are expected to change based on the medication dosage.  

   

• Extraneous Variables: These are variables that are not the focus of the study but can potentially influence the dependent variable, making it difficult to isolate the true effect of the independent variable. They can confound the results if not controlled for.
  • Example: In the medication study, factors like patient age, diet, exercise habits, and stress levels could be extraneous variables that might affect blood pressure readings, regardless of the medication.

   

Controlling Extraneous Variables

Researchers employ various strategies to minimize the impact of extraneous variables:

1. Random Assignment: Participants are randomly assigned to different groups (e.g., treatment group and control group). This helps distribute extraneous variables evenly across groups, reducing the likelihood that they will systematically bias the results.  

2. Matching: Researchers identify potential extraneous variables and then match participants in different groups based on those variables. For example, if age is a concern, researchers might ensure that each group has a similar age distribution.  

Example from a Research Article

Let’s consider a study examining the effect of mindfulness meditation on reducing anxiety levels in college students during finals week.

• Independent Variable: Mindfulness meditation (e.g., participants in the treatment group practice meditation for a set time each day).  

• Dependent Variable: Anxiety levels (measured using a standardized anxiety scale).
• Extraneous Variables: Factors like prior meditation experience, stress levels outside of finals week, sleep quality, and caffeine intake could all influence anxiety levels.

How Researchers Controlled Extraneous Variables:

• Random Assignment: Students were randomly assigned to either the meditation group or a control group (no meditation). This helped ensure that factors like pre-existing anxiety levels or stress outside of finals week were distributed evenly across the groups.
• Inclusion/Exclusion Criteria: Researchers might have included criteria such as “students with no prior experience with mindfulness meditation” to minimize the impact of prior experience as an extraneous variable.