17. A non-transitory computer readable medium storing computer executable instructions which when executed on a computer simulate a process, the instructions comprising instructions to: identify a first change made by an advertiser to a paid portion of the search advertising campaign, the first change affecting a cost of the paid portion; determine one or more effects of the first change, the one or more effects being indicative of: a change in a volume of search traffic resulting from the paid portion, and a change in a volume of search traffic resulting from an unpaid portion of the search advertising campaign; process the one or more determined effects to generate a first synergy score, wherein the first synergy score quantifies an impact of the first change on the volume of search traffic resulting from the unpaid portion; and store the first synergy score in a machine readable memory in association with an indication of the first change.
17. A non-transitory computer readable medium storing computer executable instructions which when executed on a computer simulate a process, the instructions comprising instructions to: identify a first change made by an advertiser to a paid portion of the search advertising campaign, the first change affecting a cost of the paid portion; determine one or more effects of the first change, the one or more effects being indicative of: a change in a volume of search traffic resulting from the paid portion, and a change in a volume of search traffic resulting from an unpaid portion of the search advertising campaign; process the one or more determined effects to generate a first synergy score, wherein the first synergy score quantifies an impact of the first change on the volume of search traffic resulting from the unpaid portion; and store the first synergy score in a machine readable memory in association with an indication of the first change. 19. The computer readable medium of claim 17 , wherein the one or more determined effects further include one or more effects selected from the group consisting of: one or more changes to one or more volumes of traffic from one or more organic listings, paid search listings or organic and paid search listings of the website at one or more search engines, one or more changes to one or more click-through-rates associated with one or more organic listings, paid search listings or organic and paid search listings of the website at one or more search engines, one or more changes to one or more volumes of orders associated with one or more organic listings, paid search listings or organic and paid search listings of the website at one or more search engines, one or more changes to revenue associated with one or more organic listings, paid search listings or organic and paid search listings of the website at one or more search engines, one or more changes to one or more number of page views associated with one or more organic listings, paid search listings or organic and paid search listings of the website at one or more search engines, and one or more changes to one or more whitepaper downloads associated with one or more organic listings, paid search listings or organic and paid search listings of the website at one or more search engines.