It is important to note that the DRR metric is not related to the payback of a business or a certain type of goods. When calculating it, only direct advertising costs are taken into account, for example, television or online. The formula does not take into account the cost of production and other costs not related to advertising (for this, there are POI, ROMI metrics).
It only indicates that advertising campaigns are working effectively. To get a full picture of profitability, you need to calculate other metrics.
Difficulties in defining the indicator: what needs to be taken into account and cannot be missed
It seems simple: we insert the values into the cell phone number list formula, calculate, and if the DRR is less than 100%, then the advertising is effective. However, many do not take into account how long the transaction lasts. If you are promoting sushi delivery or another "quick purchase", then there are no problems. But if your products are expensive, then the buyer decides to buy longer than the campaign lasts, and this must be taken into account in the calculation.
For example, advertising lasts for one month (March). During this time, managers receive 15 requests, 5 of which immediately buy the product, and the remaining ten move further along the sales funnel. 5 of them close the deal only in April, and another 5 in May. With a standard calculation of the DRR, we would only take into account the income and expenses for March and miss out on about 70% of the profit received thanks to the advertising campaign. With full coverage of all values, the indicator would be higher. Thus, if the sales cycle is long, then you need to either show advertising during the entire period of the consumer's movement along the sales funnel, or view the path of all requests that came from advertising, and calculate the DRR after the time has elapsed.
Another point that is often missed when determining the DRR is the profit received during the advertising placement. When evaluating outdoor, radio or TV advertising, it will not be possible to evaluate this indicator, but with digital promotion the situation is different.