There are different ways to test your programmatic campaigns and experiments, depending on your objectives, budget, and resources. Some of the most common methods are A/B testing, multivariate testing, and incrementality testing. A/B testing compares two versions of a single variable, such as a creative, a headline, or a bid strategy. Multivariate testing compares multiple variables and their combinations, such as different audiences, placements, and formats. Incrementality testing measures the causal impact of your campaign on your desired outcome, such as sales or sign-ups, by comparing a treatment group that sees your ads and a control group that does not. Each method has its advantages and limitations, so you need to choose the one that suits your needs and goals. You also need to use the right tools and platforms to run, monitor, and analyze your tests, such as Google Optimize, Facebook Experiments, or Optimizely.