If an asset is acquired on a date other than the first day of a quarter, or sold on a date other than the last, the resulting measurement is said to be a "partial period" because the asset does not have a full quarter's worth of activity during that period. Different methodologies are used to treat partial periods within the TWR calculation.
Global Definitions Database
Partial Period (for TWR purposes)
Source: NCREIF PREA Reporting Standards | Date: 29 April 2020 | ID: D0180 | Version: 3