Is it correct to analyze the effectiveness of sales of seasonal goods for the previous month?

Question

Project management

Good afternoon!
There is a project on which global promotion work has been going on for 1.5 years. The main indicators compared to previous years are very good (namely, sales, orders, profit, average check, the budget of the Republic of Kazakhstan, etc.).
At the beginning of each month, a detailed report is provided with detailed analytics for all indicators (for example, July 2017 / July 2018)
The customer has been asking for the last few months that an analytical report be provided to him in comparison with the previous month (for example, July 2018 / June 2018)
But the problem is that the promoted goods are seasonal and it is simply absurd to conduct analytics with the last month.
Q: Has anyone come across research papers on this topic? Since I have all the arguments that comparing sales of seasonal goods from month to month and drawing conclusions based on this is useless work.

Answer 1

Don't confuse "analytics" with "predictive models".
Any analytics can be built, including the one that the customer requires. But time-series forecasting cannot be carried out for the previous month. And in general, making a forecast forward one step back is nonsense.
By the way, but the seasonal component in the time series to identify and use for the forecast - after a few years of analysis, of course - will be quite within your power.

Answer 2

Is it correct to analyze the effectiveness of sales of seasonal goods for the previous month?
....
There is a project on which global promotion work has been going on for 1.5 years.

It seems to me, or have you been unable to find out in 1.5 years whether your product is seasonal, can 1/12 of a year be used for analytics?
Wait a minute, 1.5 years is 18 months!!!!
How many opportunities did you have???
The customer has been asking for the last few months that an analytical report be provided to him in comparison with the previous month (for example, July 2018 / June 2018)
But the problem is that the promoted products are seasonal and it is simply absurd to conduct analytics with the last month.
Try to explain to him that the product is seasonal.
If he doesn’t fail - score and give what he wants. He himself has the right to ruin the business as he wants.
I think he still knows better.