I'm going to answer your questions in their reverse order, because each one actually builds on the earlier answer.
What is the differences between external campaign tracking codes and marketing channels? May we get more specific explainataion in terms of the attribution approach?
External campaign tracking codes (or "Tracking Codes", for short) are the URL query that contain your campaign tracking identifier. This query could be "cid" or "cmp" or "campaign" or whatever has been designated as the parameter in your Adobe Analytics code (or Adobe Analytics extension, if you're using Adobe Launch). So every ad that links to your website should have that query in its URL. E.g. if you're linking to www.mywebsite.com/deeplink and your Tracking Code is identified by the "cmp" query, then your link should be www.mywebsite.com/deeplink?cmp=campaign-tracking-code. Then when a user lands on that deeplink page, Adobe Analytics will track "campaign-tracking-code" to the Tracking Code.
Marketing Channels are defined by the Marketing Channel Processing Rules in your report suite admin. These are a set of post-data collection rules to categorise hits into the channels, based on your own rules. For example, if a hit is collected where its Referrer is a known search engine, then that hit could be categorised under the "Natural Search" channel.
Also, may we know if marketing channels are attributed based on external campaign tracking codes? If the external campaign tracking codes are not implemented on all marketing channels, will we be seeing an incorrect picture for marketing channel?
You'll need to check your own Marketing Channels Processing Rules to answer this question. Different setups can have different rules, even for the same channels. E.g. you may use a "cid" query string to identify Paid Search, whereas I may use "Tracking Code".
However, we see a reverse trend than our hypothesis, i.e. paid marketing channels have a much lower visitors than non-paid marketing channels by first-touch dimension. May we know the rationale of this trend please?
The possible rationales are:
- Your Paid Search campaigns only started recently, so no users would have been able to enter your site through paid search ads a long time ago.
- Your Paid Search campaigns are targeting users who have already visited your website.
- (highly likely) There are links to your websites that don't have Tracking Codes, e.g. outdoor ads, links in emails / instant messages. That could explain why Direct/Bookmarked is the top First Touch channel, because people just click the untracked link.
- (most likely) Your users research about your products/services through other means, then when they're ready to buy, they search for you, find a Paid Search ad, and clickthrough.
