Abstract: Methods, apparatus, systems, and articles of manufacture to determine an additive reach adjustment factor for audience measurement are disclosed. An example apparatus for additive reach adjustment includes at least one memory, machine readable instructions, and processor circuitry to execute the machine readable instructions to identify a first probability, the first probability associated with a population tuning to a marketing campaign, the tuning including missing data, identify a second probability, the second probability associated with the population not tuning to the marketing campaign or the tuning including missing data, determine an additive reach adjustment based on a compound probability and a no-tuning probability, the compound probability and the no-tuning probability determined using the first probability and the second probability, and credit a population exposed to the marketing campaign to include missing impressions based on the additive reach adjustment.

Abstract: Methods, apparatus, systems, and articles of manufacture are disclosed to determine unified entity weights for audience measurement. Example apparatus disclosed herein are to obtain entity data associated with an entity over a period of time including a plurality of time segments, the entity data including an entity identifier, adaptable weights of the entity associated respectively with the time segments in the period of time, and panel statuses of the entity that correspond to respective ones of the time segments in the period of time, and average the adaptable weights based in the panel statuses to determine a unified weight of the entity for the period of time.