Why does FB Insights API return different values but the same dates when segmenting by days_28 / week / day / lifetime?

Question

These 3 API calls all return values for essentially the same dates (Jan-1st - Jan-30th).

/50813163906/insights/page_impressions_paid_unique/week?since=1388552400&until=1391144400

/50813163906/insights/page_impressions_paid_unique/day?since=1388552400&until=1391144400

/50813163906/insights/page_impressions_paid_unique/days_28?since=1388552400&until=1391144400

However the values for each date are hugely different.

• /week gives

  {value: 635756,end_time:"2014-01-01"},,{value: 479251,end_time: "2014-01-02"},{value: 396633,end_time: "2014-01-03"}...

• /day gives

  {value: 110598,end_time:"2014-01-01"},{value: 458,end_time: "2014-01-02"},{value: 4,end_time: "2014-01-03"}...

• /days_28 gives

  {value: 411634,end_time:"2014-01-01"},{value: 407725,end_time: "2014-01-02"},{value: 403430,end_time: "2014-01-03"}...

what are these date segments supposed to total up and from when to when?

Answer 1

I'm pretty sure that the values given are totals for the end date dependant on your segmenting .

For example, the segment /week returns:

{value: 635756,end_time: "2014-01-01"}
{value: 479251,end_time: "2014-01-02"}
{value: 396633,end_time: "2014-01-03"}

Which means:

For the 7 days prior to & ending on *2014-01-01* there were 635756 impressions
For the 7 days prior to & ending on *2014-01-02* there were 479251 impressions
For the 7 days prior to & ending on *2014-01-03* there were 396633 impressions

---

The segment /day returns:

{value: 110598, end_time: "2014-01-01"}
{value: 458,    end_time: "2014-01-02"}
{value: 4,      end_time: "2014-01-03"}

Which means:

For the day *2014-01-01* there were 110598 impressions
For the day *2014-01-02* there were 458    impressions
For the day *2014-01-03* there were 4      impressions

---

The segment /days_28 returns:

{value: 411634, end_time: "2014-01-01"}
{value: 407725, end_time: "2014-01-02"}
{value: 403430, end_time: "2014-01-03"}

Which means:

For the 28 days prior to & ending on *2014-01-01* there were 411634 impressions
For the 28 days prior to & ending on *2014-01-02* there were 407725 impressions
For the 28 days prior to & ending on *2014-01-03* there were 403430 impressions

---

These numbers look to be about right, but your 28 days numbers seem smaller than your week numbers which is strange. Maybe that has something to do with the since & until limits that you're putting on the GET request.

If you want the true numbers for a month, it's probably best to do by day and take the individual values and using the paging next / previous values that are returned as part of the results to help you navigate backwards until you reach the first of the month.