Which of the following historical data is NOT typically needed to forecast campaign ROI?

Focusing on forecasting campaign ROI, conversion rate, impression share, and click-through rate are all crucial elements that directly influence how well a campaign performs in terms of its financial return.

Conversion rate is essential because it indicates how many visitors take the desired action after interacting with ads, which is crucial for calculating the actual return on investment. Impression share reflects how often ads are shown compared to how often they could have been shown, providing insights into overall visibility and potential reach, which can relate to ROI. Click-through rate is significant because it measures how effectively an ad encourages users to click on it, influencing traffic and potential conversions.

In contrast, bounce rate—while important for understanding user engagement and website performance—does not have a direct one-to-one correlation with campaign ROI forecasting. Bounce rate indicates the percentage of visitors who leave a site after viewing only one page and does not provide clear metrics about the financial implications or effectiveness of the campaign in driving conversions. Hence, while bounce rate provides insights into user behavior, it is less critical for directly forecasting ROI compared to the other metrics.