US Patent 7853969 Log processing to determine impression values using reliable durations

Set top box logs are received from a television provider and processed to compensate for broadcast latency and generate normalized log data, e.g., log data that are indexed to a relative time. Channel tunes and the channel tune times of the normalized log data can be compared to expected air times of television advertisements on channels, and an impression values, e.g., projected viewers, can be generated for each television advertisement.