Google Data Studio has the functionality to create your own custom metrics or calculated fields as they are called. These are handy when you are building a dashboard and want to include metrics for further insights that are not by default available in Google Analytics or the data source you are using.
In this video I am using calculated fields to calculate the percentage of drop offs from each step of the shopping funnel on an eCommerce site (in this example I am using data from the Google Merchandising Store which is publicly available.
If you have the enhanced eCommerce reports in Google Analytics enabled for your eCommerce website you have a Shopping Behavior report available to analyze how users who visit the website move along to complete a purchase. In the Google Analytics report this is visualized with bar charts and also reports on the drop off percentage from each step. These percentages however are not available as a metric to use outside the interface of Google Analytics Shopping Behavior report.
To recreate this report in Google Data Studio I am using scorecards for each metric and scorecards for each calculated metric.
This video shows how to use the calculated fields option and how to use formulas to calculate properly the metrics you need.
You can use custom metrics to calculate the drop in traffic or conversions, conversion rate for a few of your conversion goals, and many more.