According to the TV-By-The-Numbers site, Little People, Big World had ratings of 1.258 on Sunday for the 3rd special.
Although, keep in mind, the TV By The Numbers site listed ratings for the 2nd special of Little People, Big World as 1.534 and then Matt Roloff posted on his Facebook that TLC was "thrilled" at the 1.2 rating it received.
So whatever the case, the number of viewers were down from the 2nd special to the latest special.
It is important to note that Sunday night was a bad night for most cable shows due to the NFL Playoffs. The Kardashian show was down considerably from what they usually receive.
As a comparison, the TLC show that followed LPBW on Sunday night, "Hoarding Buried Alive" had a 1.324 compared to LPBW's 1.258.