2018 D-Value Revision
As mentioned in its list of changes for the 2018 Sectional Championship Tournaments and Intercollegiate Championship Tournament, NAQT has made minor revisions to the D-Value system used to compare the performance of teams at different SCTs.
The changes are based on analysis of SCT and ICT performance over the past eight years (2010 to 2017) and are expected to improve the correlation between calculated D-Value and ICT performance (measured either by final finish or points per tossup heard). One motivation for the change was the new, tier-based qualification system for the ICT in which SCT champions are no longer guaranteed an invitation.
The revised system will be used for the 2018 SCTs; it will be used for both CC SCTs and SCTs in 2019 once NAQT has had time to perform a similar analysis on the data from its community college tournaments.
The new system involves three changes:
The difficulty adjustments (DCT and DCB) used to adjust raw tossup and bonus scores for Division I teams that play on the Division II SCT question set have been changed to 0.8 (from 0.9) and 0.67 (from 0.7) respectively. (When there are fewer than four teams in either division of an SCT, the teams compete as a single, combined field using the questions appropriate for a majority of the teams.)
The calculation of opponent strength (TUPPTUHopp) for a team T now excludes from its average the games involving T itself. This prevents a strong team in a small Sectional from dramatically reducing its own D-Value by virtue of its play making every opponent look weak.
The strength-of-schedule (SOS) adjustment now has a floor of 0.75. If the strength of an SCT is calculated to be lower than 0.75, then 0.75 is used instead. NAQT found that the top teams at very weak SCTs had been undervalued by the D-Value system.
Questions and comments about these changes can be directed to NAQT at firstname.lastname@example.org.