We can share the data with you informally, but the gist of it is the plot
you linked to
https://wikitech.wikimedia.org/wiki/Analytics/Unique_Devices/Last_access_solution#How_big_of_a_percentage_does_the_offset_represent_from_the_total.3F
For uniques monthly data as of these February these are numbers for English
Wikipedia, offsets vary quite a bit according to projects and by nature of
calculation samller in mobile than desktop.
Couple data points below:
underestimate offset offset
percentage
en.m.wikipedia.org 314989256 74130374 ~20%
en.wikipedia.org 181066391 74848500 ~30%
On Fri, Apr 8, 2016 at 2:37 PM, Denny Vrandečić <[email protected]> wrote:
> Yes, how big that part is, that is what I would be curious about.
>
> On Fri, Apr 8, 2016 at 11:32 AM Nuria Ruiz <[email protected]> wrote:
>
>> >Basically, to capture only people who already have a Wikimedia-cookie,
>> and count those.
>> Ah, yes, now I get it.
>>
>> Yes. We have done these calculations and they under report by quite a bit
>> cause you need two visits to wikipedia to have a cookie (cookie is set on
>> your first visit, sent back on the 2nd visit) so as you said you will miss
>> all 1-hit visits in a monthly period, for example. Whether this matters
>> depends on user's browsing patterns, it turns out that 1-hit visits make up
>> quite a significant part of our traffic.
>>
>>
>>
>>
>> On Fri, Apr 8, 2016 at 11:22 AM, Denny Vrandečić <[email protected]>
>> wrote:
>>
>>> +Wikimedia Analytics <[email protected]>
>>>
>>> Thanks for pointing me to the list, I should have written there in the
>>> first place.
>>>
>>> Sorry, with "user agent" term, I didn't mean the actual user agent
>>> string, but rather what you are trying to express with "unique device" -
>>> i.e. the different browsers on a single mobile device. I should have just
>>> stayed with your terminology to make it less confusing.
>>>
>>> Basically, to capture only people who already have a Wikimedia-cookie,
>>> and count those. This would still underreport - as it would miss all that
>>> only came once - but not by too much, I'd think. Right now I am more
>>> worried about overreporting.
>>>
>>> I hope this is a bit clearer.
>>>
>>>
>>>
>>> On Fri, Apr 8, 2016 at 11:16 AM Nuria Ruiz <[email protected]> wrote:
>>>
>>>> Denny:
>>>>
>>>> Best list to ask these kinds of questions is analytics@ (cc-ed).
>>>>
>>>> >A minor question - could you also count the number of unique
>>>> recurring user agents per month? I.e. the number of visits that return and
>>>> have a still valid cookie (e.g. by >marking the cookie after the count).
>>>> mmm...Not sure what you mean by "recurring" as you can have thousands
>>>> of people with the same user agent, right? Think "everyone in Seattle with
>>>> an iPhone and the latest OS using Safari" . You can add other pieces of
>>>> info like IP, but in mobile and due to NAT-ing [1] that can also mean a
>>>> group of thousands of people. So it will always under-report heavily the
>>>> number of unique devices if you use "recurring user agents" as base for
>>>> your main calculation.
>>>>
>>>> Now, I might be missing something as your question is brief, maybe you
>>>> can elaborate a bit more ?
>>>>
>>>>
>>>> >I am worried that the current number, due to the freshness offset
>>>> might be overreporting
>>>> Since the offset calculation takes IP into account when looking for
>>>> freshness and it only keeps devices having 1 event without cookies and 0
>>>> with cookies the calculation is likely to under-report in mobile, due to,
>>>> again, NAT-ing and user agents being shared among many devices. We see this
>>>> on our data as smaller offset numbers in mobile projects than desktop
>>>> projects. Now, this methodology might over report for a user that uses many
>>>> distinct IPS, same browser, does 1 request and clears cookies after every
>>>> session, now this is a far less often a common of a scenario.
>>>>
>>>> Hopefully this makes sense.
>>>>
>>>>
>>>> >Again, congratulations on the work! I am really happy to see the WMF
>>>> not being dependent on a commercial traffic numbers provider anymore!
>>>> Many thanks for reading!
>>>>
>>>>
>>>>
>>>>
>>>> [1] https://en.wikipedia.org/wiki/Network_address_translation
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Fri, Apr 8, 2016 at 10:30 AM, Denny Vrandečić <[email protected]>
>>>> wrote:
>>>>
>>>>> Hi Nuria, Aaron,
>>>>>
>>>>> first congratulations on the Unique devices work! I am really
>>>>> impressed by the solution and the dataset. I am looking forward to the
>>>>> visualizations that will come out from this.
>>>>>
>>>>> A minor question - could you also count the number of unique recurring
>>>>> user agents per month? I.e. the number of visits that return and have a
>>>>> still valid cookie (e.g. by marking the cookie after the count).
>>>>>
>>>>> My reasoning is the following: knowing well that it would possibly
>>>>> further underreport the number of unique user agents, it would get rid of
>>>>> all user agents that clean their cookies out or that use some form of
>>>>> incognito mode. It would only count people who have been there, got a
>>>>> cookie, returned, and then we mark the cookie, and don't count them
>>>>> further
>>>>> until it expires.
>>>>>
>>>>> I am worried that the current number, due to the freshness offset [1],
>>>>> might be overreporting, and I do not agree fully with your reasoning in
>>>>> that page that this is OK. Counting only the recurring ones would clean
>>>>> that up, give a more reliable number, although it would potentially
>>>>> underreport the people who indeed only come once a month (a number I don't
>>>>> expect to be too large).
>>>>>
>>>>> It would be interesting to see these two numbers side by side.
>>>>>
>>>>> Again, congratulations on the work! I am really happy to see the WMF
>>>>> not being dependent on a commercial traffic numbers provider anymore!
>>>>>
>>>>> Cheers,
>>>>> Denny
>>>>>
>>>>>
>>>>> [1]
>>>>> https://wikitech.wikimedia.org/wiki/Analytics/Unique_Devices/Last_access_solution#How_big_of_a_percentage_does_the_offset_represent_from_the_total.3F
>>>>>
>>>>>
>>>>
>>>>
>>
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