Final answer:
The Time Lag Report is needed to measure the duration between a user's initial exposure and their subsequent conversion, as it shows the number of days that pass before a conversion goal is achieved.
Step-by-step explanation:
If you are looking to measure the duration between a user's first exposure to a marketing initiative and their subsequent conversion action, you would need a Time Lag Report. This type of report shows how many days pass between a user's first interaction with your brand and when they finally complete a conversion goal, such as making a purchase or signing up for a newsletter. Conversion Reports track the total number of conversions, Attribution Reports assign credit to different marketing touchpoints, and Click-through Reports show the effectiveness of clicks in a campaign. However, the Time Lag Report specifically helps in understanding the conversion delay, providing insights into how long it takes for marketing efforts to result in a conversion. Such data is critical for marketers aiming to optimize the conversion paths and shorten the sales cycle where possible.