I'm using instll_referrrer tracking the user installation. Recently, I found a lot of user send the refer utm_source=(not%20set)&utm_medium=(not%20set) to my server.
I searched this on Google, and find a artical https://plus.google.com/+AndroidDevelopers/posts/E54ae9beKLB which tell me this will be set as default for user from deeplinks. And then I searched the definition of deeplink but I don't quite understand it.
From now on, if there is no referrer parameter in the URL, a default will be set to separate organic installs from deeplinks (i.e. a third party referral to your Play Store listing).
Dose this means if I received some install_referrer with content content utm_source=(not%20set)&utm_medium=(not%20set),the user who sent these referrer have installed my app by third party referral which has a format like {scheme}://{host_path} ?
The documentation states that it only occurs when you use the deeplink (http) to the play store:
For a deep link into Google Play where the referrer parameter is not present or empty, the referrer value provided is:
utm_source=(not%20set)&utm_medium=(not%20set)
For instance:
https://play.google.com/store/apps/details?id=com.google.android.apps.maps
Documentation here: https://developers.google.com/app-conversion-tracking/third-party-trackers/android
Your URL needs to have a "referrer" parameter, and encode your referrer in there. An example is
https://play.google.com/store/apps/details?id=a&referrer=utm_source%3Dgoogle%26utm_medium%3Dcpc%26anid%3Dadmob
You can try to use this https://developers.google.com/analytics/devguides/collection/android/v4/campaigns to create examples.
来源：https://stackoverflow.com/questions/38940155/when-will-the-application-receive-a-install-referrer-with-content-utm-source-no