Advantages and disadvantages of a consumer panel?

Advantages:

• lower cost than primary data collection methods,
• rapid availability and timelineness of brand switching and shifts in buyer preferences
• accurate report of sensitive expenditures: beer, liquor, cigarettes
• high level of specificity e.g. actual products not intentions anymore
• information on aggregate sales activity and shifts in retail outlets (store performances
• Disadvantages:
• • there are possibility of selection bias which is distortion of evidence or data that arises from the way that the data are collected.
  Mortality effect
• testing effect