How can I get an alert if there are very few purchases on our site?

The answer to this question will vary based on your own context, but, we will go through all the major contexts.

With the enhanced ecommerce plug-in

First, do you have enhanced ecommerce enabled in Google Analytics? If yes, we will want to monitor the number of transactions for the ecommerce metrics in Google Analytics.

The main goal for most people for this is to know as soon as possible when there is a problem somewhere in their funnel that prevents people from buying.

In real-time

Metrics Watch offer both alerts in real-time, and alerts based on previous data. Sadly, the ecommerce metrics and dimensions are not available in the real-time API, but there are ways to make that work.

The most common and efficient workaround is to have an event sent to Google Analytics, and a goal set using that event. Why? Because we have access to goal completion metrics in real-time! All details in the section below on how to set this.

With goals

In most case, the ideal is to know right now that there is a problem with your site. Knowing a date later that there were less sales than usual is definitely useful, but does not serve the same purpose as knowing right away when there is something unusual happening, like a broken cart, for instance.If you have a high volume of traffic, you will want to do this in real-time.

If you have a high volume of traffic, you will want to do this in real-time.

First, you need a goal setup in Google Analytics to measure that.