US researchers reckon that business leaders have to tread a fine line - not assertive enough and you're considered weak, but equally people who are too assertive won't win any fans either.

Report co-author Frank Flynn, an organisational behaviour expert from Stanford Graduate School of Business, says assertiveness is the single biggest factor that determines whether someone is considered a success or a failure.

He told Management-Issues:

"The analogy we use is that assertiveness is like salt in a sauce: too much spoils the dish, but too little is equally distracting.

"While getting assertiveness wrong in one direction or the other dominates perceptions of weakness, getting it right is not a major theme in perceptions of strengths. In other words, nobody ever compliments the chef on a perfectly salted dish."