1. A method to determine demographics for non-panelist households, the method comprising: calculating, by executing an instruction via a processor, a first demographic constraint average and a second demographic constraint average based on a first demographic distribution of a first tuning event of a set-top box of a household and a second demographic distribution of a second tuning event of the set-top box, the household is a non-panelist household, the first demographic distribution includes a probability that the first tuning event is associated with a first demographic constraint and a probability that the first tuning event is associated with a second demographic constraint, the second demographic distribution includes a probability that the second tuning event is associated with the first demographic constraint and a probability that the second tuning event is associated with the second demographic constraint; based on the first demographic constraint average, determining, by executing an instruction via the processor, a first likelihood of the household being associated with the first demographic constraint; based on the second demographic constraint average, determining, by executing an instruction via the processor, a second likelihood of the household being associated with the second demographic constraint; and estimating, by executing an instruction via the processor, a household characteristic of the household based on the first likelihood and the second likelihood, the household characteristic including a number of household members of the household.