Skillet (band) 2000, Trey McClurkin parted ways with Skillet, and Lori Peters filled the drummer's position. The band released their first worship album, and fourth album overall, "Ardent Worship" in late 2000. The band kept much of their sound from "Invincible" on their next album "Alien Youth". With little time between touring and recording, Skillet released "Alien Youth" on August 28, 2001, which was the first album that John Cooper took on production duties. Before the release of "Alien Youth", Haaland left the band, and Ben Kasica took over on guitar. In 2003, "Collide", the band's sixth studio album, was released by
Differential item functioning Differential item functioning Differential item functioning (DIF) is a statistical characteristic of an item that shows the extent to which the item might be measuring different abilities for members of separate subgroups. Average item scores for subgroups having the same overall score on the test are compared to determine whether the item is measuring in essentially the same way for all subgroups. The presence of DIF requires review and judgment, and it does not necessarily indicate the presence of bias. DIF analysis provides an indication of unexpected behavior of items on a test. An item does not display DIF if