Methods and apparatus to calibrate return path data for audience measurement

A non-transitory computer readable medium comprising instructions that, when executed, cause a machine to at least:

• classify a first viewing period associated one or more segments of return path data received from a set top box into one or more tuning classifications based on the one or more segments of the return path data, the tuning classifications including live tuning and playback tuning;
• calculate a total reported tuning duration for the first viewing period when the first viewing period is classified as at least one of live or playback tuning;
• compare the total reported tuning duration to a duration threshold to determine whether the one or more segments of return path data associated with the first viewing period are valid;
• and
• rectify missing tuning data associated with a second viewing period based on tuning data included in the one or more segments of return path data associated with the first viewing period when the one or more segments of the return path data associated with the first viewing period are determined to be valid.

A method comprising:

• classifying a first viewing period associated with one or more segments of return path data received from a set top box into one or more tuning classifications based on the one or more segments of the return path data, the tuning classifications including live tuning and playback tuning;
• calculating a total reported tuning duration for the first viewing period when the first viewing period is classified as at least one of live or playback tuning;
• comparing the total reported tuning duration to a duration threshold to determine whether the one or more segments of return path data associated with the first viewing period are valid;
• and
• rectifying missing tuning data associated with a second viewing period based on tuning data included in the one or more segments of return path data associated with the first viewing period when the one segments of the return path data associated with the first viewing period are determined to be valid.