An independent variable is the factor that you suspect influences an outcome you are interested in. In a study examining the effectiveness of different email subject lines on click-through rates, the independent variable would be the email subject line variation.
For instance, if you’re conducting an A/B test with two different subject lines (“Free Shipping Today!” versus “Limited Time Offer!”), the independent variable would be the different subject lines used in the emails. The dependent variable in this scenario would be the click-through rate, as it’s the outcome being measured to determine the impact of the independent variable (email subject line variation) on user engagement.
