WNL Calculation of partial areas > tlast with BQL= 0 rule [Software]

posted by Babe_Ruth – USA, 2018-07-13 21:36 (798 d 19:52 ago) – Posting: # 19053
Views: 5,033

(edited by Babe_Ruth on 2018-07-13 22:19)

I noticed something peculiar with how WNL (currently using v 6.3) calculates partial areas where BQL is imputed with 0 for samples after Tlast.

Let's say my partial area to be calculated is AUC 0-24hr. Tlast is 12h, and every sample taken after 12h was BQL (16, 24, 48, 72 hr).

I've noticed that in the 0-24hr partial area calculation, there are differences between imputing BQL with 0 and setting it as no value.

When I set BQL to "no value," then it uses the rules stated in documentation: WNL rules for partial areas are stated here. Most notably: "If ... end time falls after the last numeric observation and λz is not estimable, the partial area will not be calculated." Requiring λz suggests that WNL does not default to another calculation method in case log-linear isn't available.

However, when I set BQL to 0, it uses a linear-trapezoidal rule: (Clast + 0)*(T16 - Tlast)

Nowhere in the documentation does it say that this was the plan.

In summary, when I set BQL to 0, calculation method for partial area changes and the values slightly differ. Is this intended? Is this normal practice? In general, the differences between the two methods of calculation is less than 1%

Edit: Please follow the Forum’s Policy. Category changed; see also this post #1[Helmut]

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