DVRs and Streaming Prompt a Shift in the Top-Rated TV Shows: Total popularity does not perfectly correlate with profitability, however, since the networks all agree to sell ad time based on a metric called “C3.” It measures the average viewing of the commercials within a show within three days of the first broadcast, so it excludes people who wait to watch Wednesday’s “Modern Family” until Sunday or Monday.
Still, advertisers are paying, happily so, for the three days that are counted.
