Glossary/Mid-price
Mid-price
Mid-price (mid) is usually (best bid + best ask) / 2 when both sides exist. It is a simple fair-value proxy that ignores size. Microprice variants weight by size at the touch for a more inventory-aware estimate.
How AymarData records it
Compute mid from bids[0] and asks[0] on any /v1/book response. Spread is provided directly; mid is left to clients so you can choose microprice or mid consistently. Widely used in Polymarket Up/Down backtests.