Offset period by amount

Hi all,

When is Offset period by amount used in program indicators? this function seems to be associated with the reporting period.


Hi @hernandezmachava,

Good question!

The short answer, from the User Guide on Program Indicators configuration

Offset period by amount : In some cases, for example cohort analytics, the boundary should be offset relative to the aggregate reporting period when running pivots and reports. The offset period by amount is used to move the current boundary either back(negative) or forward(positive) in time. The amount and period type together will determine how big the offset will be. An example can be when making a simple enrollment cohort program indicator for a 1 year cohort, it might be enough to offset each boundary of the program indicator with “-1” and “Years”

The longer answer from the Tracker Design Guide:

Period Boundary Offsets

In most scenarios, the period of the analytics query is the period when events or enrollments should take place. In a few very specific use cases of longitudinal analysis, the program indicator should evaluate tracker data from a certain amount of time before (or after) the reporting period. These are referred to as cohorts, and can be useful in a variety of contexts:

  • Dropouts: evaluating enrollments where events were expected to occur in the reporting period, but they did not take place.
  • Expected event intervals which do not align with the reporting period interval:
    • A laboratory test should be performed 6 weeks after an inpatient visit.
    • Routine hypertension management visit should be every 5 weeks, and you want to know how many had controlled blood pressure at their latest visit in the previous three months
  • Program management: an HIV cohort counts those patients who have been enrolled in ART for precisely six months sometime during the period, and of those patients, how many of them have had a Viral Load test.

When defining a period boundary, two optional values–Offset Period by amount and Period Type–define how to move (“offset”) the period boundary relative to the reporting period.

In the example below, the analytics period boundaries for an enrollment type PI are moved back one month. The offset period type is Monthly, and the Offset period by amount is -1.

This is how we create a cohort with our program indicator by shifting the analytics window to examine tracker data from a previous time frame, relative to the analytics period.

Note Period offsets with negative values will reposition the target backwards in time. Positive offset boundaries are more rare in practice, since they evaluate tracker data from after the reporting period has ended. This is an unlikely scenario for “real time analysis” in routine HIS use cases.

What‘s important from this example is to note that the enrollment boundary has simply shifted to exactly one month before the analytics period opened, and ends one month before the reporting period closes.

  • A query for the month of May shows enrollments entered for the month of April.
  • An annual query for the year of 2022 would actually evaluate all enrollments from December 1, 2021 until November 30, 2022.
  • A weekly query for week 18 2023 (May 1-7) would likewise shift one month back, and evaluate all enrollments from April 1-7 2023.

The Tracker Design Guide provides additional examples of how to use period boundary offsets effectively.

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Hi @brian,

Thank you for sharing this useful information although in my opinion there too many technical terms for me understand everything clearly.

I will read this information again and again until I grasp it.

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