# Calculating Period-over-Period Changes

### **Use Case**

Calculating period-over-period changes is essential for tracking trends and growth in key business metrics such as clicks, orders, and revenue. This guide explains how to compute period-over-period comparisons, such as week-over-week or month-over-month changes, using Reorc's semantic capabilities.

### Example: Month-over-Month Change Calculation

To calculate a period-over-period metric in Reorc, follow these steps:

**Step 1: Create the Base Measure**

* Add a new measure, `no_of_member`, and define the formula. For example, use `COUNT(DISTINCT member_id)` to count distinct members.

<figure><img src="/files/IctGlL0FwM1wvACQ7JwP" alt="" width="375"><figcaption></figcaption></figure>

**Step 2: Create the Compared Measure**

* Add another measure, for example, `no_of_member_lm` having the same formula with base measure
* Enable the **Reporting Period** feature and set the time range to **Last Month**.

<figure><img src="/files/diX5V18IcHZUAWqmw4Gp" alt="" width="375"><figcaption></figcaption></figure>

**Step 3: Calculate the Period-over-Period Change**

* Create a new measure that calculates the change between the current month and the last month.

<figure><img src="/files/6l0qK2ZCEkXnxFIWy8Bs" alt="" width="375"><figcaption></figcaption></figure>

### **Conclusion**

Reorc's rolling\_window feature allows for flexible and efficient calculation of period-over-period changes. By defining reporting period and calculated measures, users can easily track performance over time and derive meaningful insights from their data.


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