dhis2-devs team mailing list archive

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

Hi Dapo,
If you were to generate the min-max values automatically, insert them into
the database, and an authorized user was to change them, then they would be
overwritten.

You can automatically generate these values through the data administration
module by dataset and orgunit in Data Administration->Min-Max Value
Generation . The problem is you often end up with a lot of dubious values,
such as negative numbers. This is a result of the Gaussian distribution
model which is applied (without taking any skewness into effect). I have
attached a plot from a real DHIS2 database, which show sthat the
distribution of many in DHIS2 are skewed left or right (more often to the
right) . Use of an unbounded, normal distribution for calculation of the
min-max is therefore not really appropriate. The standard deviation
approach is also highly sensitive to outliers, which also creates problems
for the outlier analysis if this approach is used. Anyway, I digress. Just
wanted to highlight that the in-built functions for calculation of the
min-max are rather primitive, and may not always lead to good results.

I am not so sure about the ability to restrict the time periods for which
the mix-max is generated. I think you would end up with far too few data
points to make a meaningful standard deviation. You are really looking for
the extremes with the min-max, and restricting to such a a narrow time
interval would probably not give you these extremes.

Regards,
Jason



On Thu, Sep 19, 2013 at 11:47 PM, Dapo Adejumo <dapo_adejumo@xxxxxxxxx>wrote:

> Hi,****
>
> It will be great if the generation of min-max values can be automated
> based on a global setting ( ability to select last 3,6 or 12 months data) .
> I am curious what happens to these “hard coded” min/max values when the
> database is set to generate min/max values from the frontend – I will
> assume they are discarded since they reside in the same table? Or which
> takes precedence ? ****
>
> Thanks.****
>
> ** **
>
> ................................................****
>
> ** **
>
> *Regards,*
>
> * *
>
> *Dapo Adejumo*
>
> *+234803363677*
>
> *skype : dapojorge*
>
> ** **
>
> *From:* Dhis2-devs [mailto:dhis2-devs-bounces+dapo_adejumo=
> yahoo.com@xxxxxxxxxxxxxxxxxxx] *On Behalf Of *Jason Pickering
> *Sent:* Thursday, September 19, 2013 6:28 PM
> *To:* Juma Lungo
> *Cc:* dhis2-devs
>
> *Subject:* Re: [Dhis2-devs] Setting MinMax Values****
>
> ** **
>
> I think I agree with Lars as well. Our use case was we wanted to restrict
> values between 0 and 31, and not do it with a validation rule, to provide
> visual clues during data entry. ****
>
> ** **
>
> As an aside, one may also want to calculate these values and save them to
> the database. The current algorithm uses a standard deviation approach,
> which is problematic, in that in many cases the data which is typically
> observed does not follow a normal Gaussian distribution. Other statistical
> models often provide better estimates of the mix/max, but currently, cannot
> be calculated automatically by the system. If these values are calculated
> externally in some statistical package, they can be inserted back into the
> system (or even automated). ****
>
> ** **
>
> Regards,****
>
> Jason****
>
> ** **
>
> ** **
>
> On Thu, Sep 19, 2013 at 6:25 PM, Juma Lungo <jlungo@xxxxxxxxx> wrote:****
>
> I agree with Lars****
>
> ** **
>
> Lungo****
>
> ** **
> ------------------------------
>
> *From:* Lars Helge Øverland <larshelge@xxxxxxxxx>
> *To:* Jason Pickering <jason.p.pickering@xxxxxxxxx>
> *Cc:* dhis2-devs <dhis2-devs@xxxxxxxxxxxxxxxxxxx>
> *Sent:* Thursday, September 19, 2013 2:43 PM
> *Subject:* Re: [Dhis2-devs] Setting MinMax Values****
>
> ** **
>
> Hi Conrad,****
>
> ** **
>
> the min-max data element is per org unit and data element like you say, so
> it applies to all current and future periods by definition. I don't know
> your use-case... but in general one might want to think twice before
> setting the same max value for all facilities, since they usually have very
> different catchment population and hence natural variations in numbers.***
> *
>
> ** **
>
> Lars****
>
> ** **
>
> ** **
>
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