WOM drives sales

Word of mouth is the "primary factor" behind between 20% and 50% of
purchases (McKinsey 2010). 

WOM is trustworthy

90% trust recommendations from people they know (Nielsen, Global Online Survey, 2009).

WOM happens offline

Still 90% of conversations happen offline (Keller & Fay, 2012) and online data does not mirror offline behavior very well (Peres & Shachar, 2010).