Accounting for an investor's time horizon needs a rethink now that investments are no longer closely tied to singular investment objectives.A specific subset of investible assets may have a time horizon, but the notion of a single time horizon is nonsensical when applied (as it often is) to an investor’s holistic situation. Each investor has multiple time horizons, because they have multiple withdrawal points and multiple goals.Good risk capacity measurements manage time horizons automatically.

Personal finance is behavioural finance.Blending behavioural psychology with quantitative-finance theory employs the best of both human and algorithmic worlds. Humans concentrate on what they’re best at – empathy, values, conversation, navigating ambiguity, creating an environment for making comfortable and confident choices – while machines take on information-filtering, monitoring, and data-processing.There is nothing rational about offering a theoretically perfect solution in the knowledge that, as an imperfect human, the investor will fail to last the distance. The rational path is to provide an accurate scientific diagnosis of the best strategy each investor can stomach, and then offer an appropriate prescription.