How to write around publication lag
- Find the typical publication lag. Check how long after the measured month the index normally releases. BLS PPI data is usually out within about ten to fifteen days of month end; other indices differ.
- Name the release date for each adjustment. State which specific index release applies to each adjustment date, so there is no argument about whether to wait or use an earlier month.
- Specify preliminary or final value. Many indices publish a preliminary value and later revise it. State which one the clause uses.
- Say what happens if the release is delayed. Give a fallback for a late release, such as using the prior confirmed value and truing up on the next cycle.
- Put a buffer before the adjustment date. Set the adjustment date at least a month after the relevant index is normally published, rather than on top of it.
What publication lag is
An index for March does not come out in March. Statistical agencies need time to collect and check data, so the March value publishes in April, sometimes later. That delay is the publication lag, and it differs by index and by country. BLS Producer Price Index data typically publishes within about two weeks after the month it covers, commonly ten to fifteen days.
Why it causes disputes
A clause that says "apply the adjustment on the 1st of the month, using that month's index" has a problem: if that month's index has not been published yet, there is no value to apply. Both sides are left guessing whether to wait, use last month's value, or use a preliminary estimate that might still change.
A worked example
A clause adjusts prices on the 1st of every month using that same month's index. The index for month N does not publish until roughly the middle of month N+1. On adjustment day, the required number does not exist yet. Every single cycle, both sides face the same argument about what to do instead, unless the clause already answers it.
Preliminary versus final values
Many indices publish a preliminary value first, then revise it once more data comes in. A clause that does not say which one to use invites an argument later, especially if the preliminary and final numbers differ enough to matter.
How to write around it
State three things in the clause: which specific release date applies to each adjustment date, whether the preliminary or final value applies, and what happens if the expected release is delayed. Naming the exact index vintage removes the argument before it starts.
Build in a buffer, not a coincidence
Pick an adjustment date that comes safely after the relevant index is normally published, not right on top of it. A one-month buffer between when the data is expected and when the adjustment takes effect avoids most publication-lag disputes without any other change to the clause.