Google Analytics cannot collect data from which systems by default?

Data Import lets you upload data from external sources and combine it with data you collect via Analytics. You can then use Analytics to organize and analyze all of your data in ways that better reflect your business. Data Import lets you join the data generated by your offline business systems with the online data collected by Analytics. However, Google Analytics does not collect offline data by default. Tip: When you configure Data Import, you create a Data Set, which defines one or more dimensions to use as a key. Data Import uses this key to match values in the uploaded data to values in your collected hit data.