Why ‘ROI is a major factor in Affiliate Marketing or small business’? Why need to know the places to learn ‘how to increase ROI’? You might be thinking these issues. Suppose, you have a pretty sound portfolio in your affiliate marketing which includes 10 types of investment and you require a measurement, competitive performance of each one so that you could figure out to select the best ones prioritizing investment. Then, which method do you prefer to follow? ROI.