Another criticism of the measuring system itself is that it fails the most important sample criterion: it is not random. A small fraction of the population is selected, and only those accepted are used as the sample size. In many local areas during the 1990s, the difference between a rating that kept a show on the air and one that would cancel it was so small as to be statistically insignificant. Yet, the show with the higher rating would survive. In addition, the Nielsen ratings encouraged a strong push for demographic measurements. This caused problems with households with multiple television sets or households where viewers would enter the simpler codes (usually their child's), raising serious questions about the demographic data quality. The situation further deteriorated as the popularity of cable television increased the number of viewable networks to the extent that the margin of error has increased because the sampling sizes are too small. Compounding matters is that of the sample data that is collected, advertisers will not pay for time shifted programs (those that are recorded for replay at a different time), rendering the "raw" numbers useless from a statistical point of view. Even in 2013, it was noted that Internet streams of television programs were still not counted because they had either no ads (such as Netflix) or totally different advertising (such as Hulu) than their television counterparts, effectively skewing the raw data on a show's popularity.