A data collection plan typically comes into the picture in the measure phase of the DMAIC six sigma methodology and is an activity done for gathering baseline data as well as other data to help understand variations and root causes of problems.  A data collection plan is established to understand  Purpose of data collection,  What type of data needs to be collected,  Where to collect the data,  How to plan the collection,  When to collect the same, and  Who would be responsible for collecting it  The plan is thoroughly thought through and includes details on the operational definition of the measure for data collection as well as the relevant sampling plans. So essentially a quality manager will be involved in streamlining the data collection per the above points to fulfill the measure phase of the DMAIC methodology.