Final answer:
An informal definition of a recession is at least six consecutive quarters of declining real GDP.
Step-by-step explanation:
An informal definition of a recession is at least six consecutive quarters of declining real GDP. A recession is a period of decline in total output, income, employment, and trade, usually lasting six months to a year and marked by widespread contractions in many sectors of the economy. The average duration of recessions in the post-WWII period is around eleven months, or slightly less than a year.