What exactly people mean when they say "X is a $Y billion industry"? I'm reading the "Personal MBA" book right now and it says that "Yoga is $8 billion industry worldwide". What does it mean? And how can one calculate the amount of money in some industry?
Considering the economic of world as a whole it could simply refers to that total spending by people on yoga might be \$8 billion. As in an economy total spending is the total revenue of a sector. For this particular scenario it simply means that yoga as an economic variable have transaction of \$8 billion.
Regarding the calculation we can de assured that no exact and absolute calculation could be made on national level how could it be calculated exactly at global level. However the estimated aggregated spending on yoga sector nation could be determined. Which further on processing might result to provied aggregate global spending on yoga as a figure, which is tentative not exact figure.