When deciding whether or not to collect a piece of data, there is a simple question that will help you decide: "What action will I take on this data, either immediately or in the long-term?" If you can't answer that question clearly, then you don't need to collect that data. (Note: An answer of "Well, we might use it in the future" is the same as answering "We will take no action on this data.")

For example, suppose during a given event registration, you ask for the following data:

• dietary restrictions
• accessibility needs (ADA)
• select which sessions you will attend
• tell me your highest level of education (e.g., bachelor's, master's, Ph.D.)

Do you need to collect all of this data? For each one, ask "What action will I take on this data, either immediately or in the long-term?"  The answers might look like this:

• dietary restrictions - IMMEDIATE (Tells us if we need to provide alternative meals)
• accessibility needs (ADA) - IMMEDIATE (Tells us if we need to provide alternative access options)
• select which sessions you will attend - IMMEDIATE (Tells us how big we need to make each room for sessions)
• tell me your highest level of education (e.g., bachelor's, master's, Ph.D.) - UNCLEAR (there is no immediate need because we won't change anything for the event based on this response, and there is no specific long-term usage identified for this data)

There is a great temptation to collect lots of data whenever we can, on the assumption that more data is better than less. But if you've got no clear plans for taking action on the data provided, then don't collect it.