Why is Wattage not an exact science?

[thegreatfuzz]

I am curious, Why do some manufacturers rate the Watt output of their amps lower then lab tests? is it not an exact science? Do the units in a certain range vary according to the manufacturing quality? help a noob understand.  :thinking:

 

[d0dja]

 

[Family_Dog]

 

[Shonver]

 

[Ampdog]

 

[KennyR]

 

[Heinrich]

 

[Blackjack]

 

[Shonver]

 

[Blackjack]

 

[thegreatfuzz]

 

[thegreatfuzz]

 

[Shonver]

 

[Blackjack]

 

[Shonver]