Lever 1 — Saves predict outbound clicks (much better than impressions)
The strongest correlation in the dataset: pins with high save rate (saves / impression) produced 4.2× the outbound clicks of pins with average save rate, controlling for impression volume.
Mechanism: Pinterest's algorithm aggressively boosts pins that get saved early, because saves signal future intent. A pin saved at hour 6 enters multiple users' boards and re-circulates in their followers' feeds for weeks. A pin with high impressions but low saves gets a one-shot impression burst and dies.
Practical implication: optimize for save rate first, not impression count. The single biggest move that lifts save rate is making the pin clearly useful at first glance — i.e., the text overlay describes a concrete outcome ('how to triple your dividend yield' beats 'investing tips for beginners'). Specificity drives saves, saves drive clicks.