Obviously, using only information up to t − ∆ has averse effects on correctness as well, as this measure evaluates the word sequences up to w gold t which may already contain more words (those recognised in ]t − ∆, t]).
to be more fair and to account for the lag when measuring the module's correctness, we additionally define fair r-correctness which restricts the evaluation up to time t − ∆: w hypt t−∆ = w gold t−∆ .