Using history to define category seasonality and/or sales curves is common practice when planning your future forecasts and strategies. For those who use 4-5-4 (or 4-4-5) retail calendars, you will eventually run into a 53 week year. This is like a reset of the calendar so your week 1 of your start month doesn't begin in the middle of the month. NRF calendars are published to try and create a standard but not everyone follows it as it doesn't fit their business model or financial practices.
However there are other factors that do happen that can change how your seasonality will spread out. Take Black Friday and Cyber Monday for example. These holidays are in 2 different weeks and are not always the same date. So year over year they may not land in the same retail week.
In the below calendar you can see that the 2024 lines up nicely with the 2023 restated calendar. In 2024, the year started on 2/4/2024 and in 2023 restated, 2/5/2023. The non-restated 2023 calendar started on 1/29/2023. This would cause our seasonality to be shifted by a week.
However, you can see that Thanksgiving lands in week 4 of Nov for 2024 (11/28/2024) and since the 2023 calendar is restated (trailing 52 weeks) it would land in week 42 (11/23/2023). This also means that Cyber Monday gets pushed into Dec wk 1 of 2024.
When comparing your holiday selling you may want to compare the 2024 calendar to non-restated 2023 calendar so these holidays line up.
In Toolio Settings/Organizational Settings/Calendars you can choose what you want to show in your Act LY variant by week. Since you can have multiple calendars for your multi-plan Merchandise Plan module you will need to select the correct row and right-click to expose the context menu.
Selecting the Open Custom Last Year Period Mapping will bring you into the page where you can ADD these configurations. Click on the ADD button and a menu will open where you can select any weeks you want to use for your comparison.
As described above, I want to use my Nov Week 3 2023 restated calendar (Nov Week 4 2023 non-restated calendar) as the comparison for Nov Week 4 2024.
So I would select:
I know what you are probably thinking..."That is the same week as you have in 2024!" True, but by default the Act LY variant is a trailing 52 weeks and since 2023 was a 53 week year for this configuration, the Act LY variant in my plan would show week 44 data. Example:
Notice how for Week 43 the LY date range is Nov 26 2023 - Dec 2 2023; If I was to change my timeframe filter to be 2023, the dates would be Nov 19 2023 - Nov 25 2023.
Now I will implement the new mapping and refresh my page to show the same comparison as above to get the expected result.
Holidays are not the only use case for this however. Marketing events or major product drops can happen at different periods and this would be a way to line up your LY.
The Forecast Functions do not currently reference the Custom Last Year Period Mapping.