[pesfandiar]

I have no intention of starting an argument, but to add value to the thread. I take the bait though:

1. "likelyhood [sic] of 1" means 100% probability. Any likelihood over 1 is by definition impossible.

2. I assumed by "there's usually two parts" and "external paid marketing", you meant people have to pay for marketing. I added my personal experience to the conversation that it's not necessarily the only option.

[MalcolmDiggs]

Again, you're wrong. And yes, you clearly have every intention of starting an argument.

1. If you'd simply read the link (which you clearly have not done), you'd understand that a k-value of 2.0 means that each customer referred an average of 2 new customers. I never said "probability". You did. Yes, probability above 1 is impossible, which is why I never used that word. You clearly conflated the two, which is your error, not mine.

Here's why I said "likelyhood" (likelihood) instead of "probability": http://stats.stackexchange.com/a/2645

"...the likelihood function does not obey the laws of probability (for example, it's not bound to the [0, 1] interval). "

2. Reading-comprehension. It's not that hard.