dhis2-devs team mailing list archive

[Jason Pickering <jason.p.pickering@xxxxxxxxx>]

Here I go again, this time on categories/category options/category
combinations.

The concept I want to address is that of dimensional hierarchy within a set
of data elements. Let me try my ASCII art skills here..


Total foos distributed

__________________________|____________________________________________
                                                          |


|
                          Total foos distributed to
wogs
Total foos distributed to zooks
                                    |                        |

                        |                                  |

Total foos distributed to blue wogs   Total foos distributed to green
wogs                   Total foos distributed to blue wogs
  Total foos distributed to green zooks

In this example, the data element "Total foos distributed" is the sum of its
component parts. Perhaps it is also collected at various locations which
have certain types themselves, which will serve as a dimension later on in
this example. Perhaps we also collect information on the number of "bars"
distributed as well, which has a corresponding disaggregation hierarchy  as
presented above.

 Let's assign the first level a dimension of "Parent data element", the
second level "Type" and the third level "Color".
I am being purposeful abstract here, but in practice these dimensions might
correspond to disaggregation dimensions "Age", "Gender", ARV Treatment
regimen", etc in a real system.

My limited understanding of the Data element category is as follows. In my
example here, I would have three  categories (Item, Creature, and Color).
The first category (Item) might contain the following category options
(Foos, Bars). The second  category (Creature) would contain the following
options (Wogs, zooks), while the third level category (Color) could contain
the options (Blue, Green).

Where am I going with this you ask? Well, I would like to be able to
pivot/crosstab my data on these possible dimensions, to see how many foos
have been distributed to green creatures in rural locations. I might want to
know how many Foos and Bars have been distributed to only wogs at private
facilities (another dimension). A PivotTable, along with the appropriate
data source, would allow me to do this.

Now, when I look at the current implementation of the Data element
categories, it is not clear to me how I might be able to accomplish this. I
can create these dimensions (categories in DHIS-speak), and assign elements
(category options in DHIS-speak) to them. I can then assign a number of
dimensions (categories) to a category option. I can then assign a data
element to a category option, which translate essentially to assigning a
dimensionality to the data element.

However, there does seem to be the ability to assign dimensions, there does
not seem to be the ability to assign particular elements within those
dimensions to a particular DHIS data element.

 Am I missing something here?

Let me ramble on. There is the ability, through organizational unit group
sets to assign dimensionality to a certain organizational unit. (Ownership
type, urban/rural, facility type). It would seem to me that the
organizational unit is simply another dimension, albeit a fundamental one
within DHIS and most Health information systems. Nonetheless, it is a
dimension, that amends itself to production of data sets that can be
crosstabbed on various dimensions (different organizational unit groups).

However, it would seem that the data element itself, as currently defined in
both DHIS 1.4 and 2, lack this intrinsic notion of dimensionality.

It would seem that the final data set that should be present in a given
crosstab table would be the Cartesian product of each of its possible the
dimensions trimmed for values that result in NULLs (e.g Location, Ownership
Type, Urban/Rural/Facility Type, Item, Creature, Color in my given example).
This does not seem to be the case to me at the moment, but perhaps I am
missing something?

Thoughts?

Regards,
Jason