“Half my advertising is wasted but I do not know which half.”
William Lever, 1st Viscount Leverhulme (1851–1925) English industrialist, philanthropist, and politician
Lord Leverhulme, as cited in: John Sherman Wright, John E. Mertes (1974), Advertising's role in society, p. 78
This quote has also been attributed to John Wanamaker and George Washington Hill