Set the max_lag parameter
Stay organized with collections
Save and categorize content based on your preferences.
The Meridian model allows for media at time \(t\) to affect the KPI at
times \(t, t + 1, \dots , t + L\) where the integer \(L\) is a
hyperparameter set by the user using max_lag
of ModelSpec
. Media can
potentially have a long effect that can go beyond max_lag
. However, the lagged
effect of media converges towards zero, due to the model assumption of geometric
decay.
In practice, max_lag
is used to truncate how long media can have
an effect because it has positive benefits including improved model
convergence, reasonable model runtimes, and maximizing data usage (reducing
variance). Keeping the max_lag
in the 2-10 range leads to a good balance of
these advantages and disadvantages.
Increasing max_lag
doesn't necessarily mean that ROI estimates
will also increase. One reason for this is because if the media at time \(t\)
can affect the KPI at time \(t+L\), this can take away from the effect of
media at times \(t+1, \dots , t+L\) on the KPI at time \(t+L\).
Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.0 License, and code samples are licensed under the Apache 2.0 License. For details, see the Google Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.
Last updated 2024-11-14 UTC.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2024-11-14 UTC."],[[["The Meridian model assumes media impact on KPIs can extend over a period, defined by `max_lag`, with the effect diminishing over time due to geometric decay."],["While media impact can theoretically last longer than `max_lag`, it's truncated for practical reasons like model convergence, runtime, and data utilization."],["A `max_lag` value between 2 and 10 generally provides an optimal balance between model performance and efficiency."],["Increasing `max_lag` might not result in higher ROI estimates, as it can redistribute the attributed impact across different media exposures over time."]]],[]]