# dhis2-devs team mailing list archive

## Re: Average Sum in Org unit Hierarchy

```Hi Lars,
definitely be a good feature to have. However in my example screen shot the
value for one month e.g. July is 20 and since it was collected for one week
then the average is 20/1 which is 20. What the system is doing is 20
/(31/7) = 4.5,given July has 31 days which means the system is including
weeks in which no data was collected and mathematically this is incorrect.
If formula for calculating this can be fixed to be a count of the weeks in
which data is entered (including zeroes) then it would be mathematically
correct instead of including periods in which no data is collected.
rgds
David

2016-11-17 20:49 GMT+03:00 Lars Helge Øverland <lars@xxxxxxxxx>:

> Hi David,
>
> the way the average+sum aggregation works is roughly this:
>
>
> sum( [days in data period] X data value ) / [days-in-aggregation-period]
>
>
> In other words, we take the sum of the product of no of days in the data
> value period and data value, divided by no of days in aggregation period.
>
> Data value period is the period for which the raw data is collected
> (weekly in your case). Aggregation period is the period which is requested
> in analytics (monthly and quarterly in your case).
>
> So in this case, the problem is that you capture data by weeks which in
> reality represent bi-weeks - this confuses the aggregation output. The
> holes in the data (you have many weeks without data) will pull down the
> average score. Based on the rules outlined the results seems correct from
> what I can see.
>
>
> We could rather look into adding support for a bi-weekly period type.
>
>
> best regards,
>
> Lars
>
>
>
> On Wed, Nov 16, 2016 at 2:24 PM, David Muturi <dnmuturi@xxxxxxxxx> wrote:
>
>> Hi Lars,
>> Many thanks for your response, since we do not have biweekly defined as a
>> dhis2 period type(which would be great to have), we have configured the
>> dataset to be weekly but only that data is entered on a biweekly basis,
>> meaning one week will miss data while another will have based on when it
>> was collected. I have attached an excel download from the datavalues table
>> as well as a screen shot showing the weekly periods that data is collected.
>> rgds
>> David
>>
>> 2016-11-16 14:08 GMT+03:00 Lars Helge Øverland <lars@xxxxxxxxx>:
>>
>>> Hi David,
>>>
>>> sounds strange indeed. We need some more info. Can you include bi-weekly
>>> periods in your screenshot so that we can see what the original captured
>>> value is?
>>>
>>> regards,
>>>
>>> Lars
>>>
>>>
>>>
>>> On Mon, Nov 14, 2016 at 8:50 PM, David Muturi <dnmuturi@xxxxxxxxx>
>>> wrote:
>>>
>>>> Hi Team,
>>>> I have a data element set us Average sum in org unit hierarchy and
>>>> collected on a bi weekly basis, when I select the data in the pivot table,
>>>> the average values are bizarre(see attachment). Is this how the above
>>>> aggregation operator is meant to work or its a bug?
>>>> rgds
>>>> David
>>>>
>>>> _______________________________________________
>>>> Post to     : dhis2-devs@xxxxxxxxxxxxxxxxxxx
>>>>
>>>>
>>>
>>>
>>> --
>>> Lars Helge Øverland
>>> University of Oslo
>>> Skype: larshelgeoverland
>>> lars@xxxxxxxxx
>>> http://www.dhis2.org <https://www.dhis2.org/>
>>>
>>>
>>
>
>
> --
> Lars Helge Øverland