persistency

The state or characteristic of being persistent.

By this hand thou, thinkeſt me as farre in the diuels booke, as thou and Falſtaffe, for obduracie and perſiſtancie, let the end trie the man, [...]

On entering her room he had been struck by the absence of that saucy independence usually apparent in her bearing towards him, notwithstanding the persistency with which he had hovered near her for the previous month.

A measure of how much something persists.

The table shows that three-year "persistencies" range from 89.6 per cent with Standard Life (this means only 10 per cent of plans have lapsed after three years) to 58.9 per cent with Sun Life (almost 40 per cent of plans lapse after three years).