2x2 factorial design

Question

Using a 2x2 factorial design 10,000 patients who were preparing to undergo non-cardiac surgery and were at risk for vascular complications were assigned to receive aspirin or placebo and clonidine or placebo.

What are the IV, DV, control and experimental variables? Also, what is one possible confound?

Answer 1

In the 2x2 factorial design study described, the independent variables (IV), dependent variable (DV), control variables, and experimental variables can be identified as follows:

Independent Variables (IV)

1. Aspirin vs. Placebo: This is the first independent variable, with two levels: patients receiving either aspirin or a placebo.
2. Clonidine vs. Placebo: This is the second independent variable, also with two levels: patients receiving either clonidine or a placebo.

Dependent Variable (DV)

1. Vascular Complications: This is the dependent variable, representing the outcome of interest, such as the occurrence of vascular complications in patients undergoing non-cardiac surgery.

Control Variables

1. Surgery Type: The type of non-cardiac surgery being performed, which could be controlled to ensure consistency across the study groups.
2. Patient Demographics: Factors such as age, gender, and pre-existing medical conditions could be controlled to minimize their influence on the outcomes.

Experimental Variables

1. Aspirin and Clonidine Interaction: The interaction between aspirin and clonidine represents an experimental variable, as the study aims to investigate the combined effects of these medications on vascular complications.

Possible Confound

1. Pre-Existing Medical Conditions: The presence of pre-existing medical conditions in some patients could potentially confound the results, as these conditions may independently influence the risk of vascular complications. Controlling for these conditions or conducting subgroup analyses may be necessary to address this potential confound.

In fact, this type of study provides with a factorial design allows for the investigation of the individual and combined effects of aspirin and clonidine on the risk of vascular complications in patients undergoing non-cardiac surgery.

I hope I could help!