Calculation of "Absolute Unique Visitors"

[mschenkel]

Sorry if this post is beating a dead horse. I have searched for hours
through post on this forum and find myself more confused than when I
started.

Essentially I want to be able to produce the numbers associated with
the "Absolute Unique Visitors" in Google Analytics. Is this possible?

I found a number of posts referencing a "new metric" which is to be
released at some point. Another post explaining that the "Visitor"
metric is only "Absolute Unique" for one day and that it is not
possible so "summarize" it across multiple days. And others
indicating the necessary metric required to calculate this is only
available in the custom reporting of GA and not in the API. But even
within Google Analytics I am not able to "drill down" and calculate
the number based on daily figures the way you can pageviews or
visits. Example: the "Absolute Unique Visitors" for a two day period
might be 1000. If you drill down day one might be 495, while day two
might be 510 (which sums to 1005). But why is the summary 1000?


In the following thread there is talk of a new metric which will aid
in the calculation (my apologies - I would have "replied" to this
post, but there is no option to reply). On 12/01/2010 Nick say he is
waiting too:
http://groups.google.com/group/google-analytics-data-export-api/browse_thread/thread/5e8ad5572f46cfda/bf9a9d9c9c0845a4?lnk=gst&q=unique+visitors#bf9a9d9c9c0845a4

Also in this thread there is a reference to the new metric request:
http://code.google.com/p/gdata-issues/issues/detail?id=2052&colspec=API%20ID%20Type%20Status%20Priority%20Stars%20Summary

And on Jan 26, 2011 it states is has been released.

But I still cannot generate the exact number. Is it possible? Or is
it still a new feature request?

Thanks,
Mark.

[Nick]

Right now there is ga:visitors.

This is the best unique visitor calculation you will get with Google Analytics.

You can get started reading this blog post: http://analytics.blogspot.com/2011/02/mastering-unique-visitors-in-api.html

-Nick

[mschenkel]

Thank you very much for the reply Nick. If you could kindly reply, as
of now there is No Way to retrieve/calculate the number outlined in
green on the screen shot below using the Google Analytics API. Is
this what you are basically saying?

http://www.embeddedanalytics.com/img/jh_AbsoluteUniqueVisitors.jpg

I am in a position where someone using our service with the
ga:visitors metric is adamant that at one point this number could be
retrieved. But I have been trying every which way to get GA API to
get it with no success. In the end I believe there may have been some
confusion with the ga:PageViews or ga:Visits metrics. These I have
been able to get with the API.

Thank you very much for your assistance on this.

Mark.

[Mike Sullivan]

Query ga:visitors for the period of your report, specifying &start-date= and &end-date=  accordingly. The number should match your highlighted number.

Do NOT include any dimension. 

[mschenkel]

Mike - Thanks. I will give that a try. I can recall seeing other
posts saying not to include a dimension.

[mschenkel]

Mike,

Thank you very much. The omission of the dimension was the critical
element in this instance. The service I have created requires a
dimension. So ALL feeds I was doing included a dimension (typically
either date or month). It is all making sense now.

Revisiting my two day example: on day one there was 495 unique
visitors, day two had 510. This sums to 1005. But over the course of
these two days GA reports there were only 1000 visitors and not 1005.
The extra 5 visitors are people who visited the site on both days.
Correct?

Now if I want to create a line chart of "Monthly Absolute Unique
Visitors" for the year 2010, the approach would be to create 12
separate data feeds where metric is ga:visitors, no dimension, and
date range set to dates for the individual month. There simply is NO
WAY to do this in one feed (e.g. ga:dimension = month or ga:dimension
= date and then sum up for each month).

Then you again Mike and Nick for your assistance here.

[Nick]

Right, dimensions are optional parameters. All score card / top level metrics in the GA UI are queried without specifying dimensions.

You are also right, you can not sum visitors across dates. The uniqueness is across the date ranges, so you will end up double counting.

In your case the extra 5 visitors will be people who visited across both days.

To get monthly uniques you can use the ga:month dimension. But months don't always have the same number of days, so you have to consider if this will really solve what you are trying to do.

-Nick

[mschenkel]

Ok - after a lot of "connecting the dots" I think everything is
finally making sense. Ultimately my problem is related to this bug
regarding "gaid::-1":
http://groups.google.com/group/google-analytics-data-export-api/browse_thread/thread/c3dbfccfaa1e5568/47658852b89a08df?lnk=gst&q=gaid#47658852b89a08df

Once I suppressed the use of gaid::-1 in my feeds my charts display
the same values as the "Absolute Unique Visitors" statistics. But
without knowing this I was led to believe that perhaps I had modified
the way I was calculating.

What I don't know is if this gaid::-1 is a recent bug, or if it has
always been a bug but that I just recently started to include gaid::-1
in my feeds.

Anyways I am all set: I am able to regenerate the numbers my customer
was once getting by excluding gaid::-1 from my feeds.