> ## Documentation index
> Fetch the complete documentation index at: https://docs.prescientai.com/llms.txt
> Use this file to discover all available pages before exploring further. Add `.md` to any page URL to get that page as Markdown.

# Compare two periods

> How to turn on Compare on the Attribution page, select the earlier period, and show each change as a percentage or an amount.

**Compare** sets the selected period against an earlier period. With **Compare** on, the summary cards, the chart, the table, and the flows show the change between the two periods. **Compare** is off when you open the page.

## How do you turn on a comparison?

The **Compare** menu in the filter bar has a switch and a list of earlier periods.

![The Compare menu, with the Compare switch and five comparison periods from Previous period to Custom period](https://docs.prescientai.com/_astro/compare-menu.BMn2hNoG_1DFAlc.webp)

1. Set the date range that you want to study.

2. Select **Compare** in the filter bar.

3. Under **Against**, select a comparison period.

   The selection turns the comparison on. Each period in the list shows its dates, except **Custom period** before you set its start. The first selection is **Previous period**.

4. Under **Show change as**, select **%** or **Amount**.

   The first selection is **%**.

The button in the filter bar then names the comparison period, for example **vs Previous**.

## Which comparison periods can you select?

| Period                | Dates that the period covers                                                                       |
| --------------------- | -------------------------------------------------------------------------------------------------- |
| **Previous period**   | The period of the same length that ends the day before the selected period starts.                 |
| **A month earlier**   | The selected period moved back 1 month. With weekly granularity, the period moves back 4 weeks.    |
| **A quarter earlier** | The selected period moved back 3 months. With weekly granularity, the period moves back 13 weeks.  |
| **A year earlier**    | The selected period moved back 12 months. With weekly granularity, the period moves back 52 weeks. |
| **Custom period**     | A period of the same length that starts on a day that you select.                                  |

The month, quarter, and year options move your selected period back in time. These options do not select a calendar month, quarter, or year.

## How do you set a custom period?

1. Select **Custom period** under **Against**.

2. Select the start day on the calendar.

   The custom period has the same length as your selected period, so you select only the start.

3. Select **Custom period** at the top of the calendar to return to the list.

## How do you turn off the comparison?

Select the button in the filter bar and turn off the **Compare** switch. The changes disappear from each section.

**Compare** also returns to off when you load the page again.