Is Facebook advertising more effective if you already have a large fan base? Say a page with 50k vs one with 250k
Answer by Tomas Dueñas Uribe:
Whenever the FB ad is a sponsored story, the amount of initial fans and their engagement, elevate that ad's effectiveness. The logic behind it is that people tend to have a higher desire to interact with the post, if the number of people already interacting with it is high. General social validation and approval is a variable that affects almost every decision we make in life.
As a second reason, a sponsored story tends to target friends of fans that have liked the post. When you sponsor a post that already has good and relevant interaction, the amount of people that Facebook has to show the post in order to get an interaction is lower. Therefore, having a higher amount of probabilities of organic interactions before the promotion, will increase the overall effectivity of the campaign.
Whenever the FB ad is not related to the Fan Page and is just a picture and a link that appears on the right hand column of Facebook, the amount of fans has no bearings upon its effectivity. The determining factors are the quality of the copy, the attractiveness of the image, and the targeted audience. The right balance between the three will drive a campaign's effectiveness. You need sufficient A/B testing between different combinations, in order to get a sense of what an appropriate CTR and CPM is within your subject.