yeartoyear

Yeartoyear, often written year-over-year or YoY, is a statistical comparison method used to measure changes from one year to the next. It is widely used in finance, economics, and business to assess growth, inflation, demand, and other time-series indicators while helping to account for seasonal patterns.

The YoY growth rate is calculated as (Value in the current period − Value in the same period last year) / Value in the same period last year × 100%. For example, sales of 120 in 2024 versus 100 in 2023 yield a 20% YoY increase.

Applications include comparing quarterly or annual figures by corresponding periods, using rolling year comparisons, and adjusting for currency effects with constant currency measures. It is preferred when a straightforward annual comparison is needed and when seasonality must be considered.

Limitations include potential distortion by one-off events, changes in accounting methods or scope, and shifts in seasonality that extend beyond a single year. Relying solely on YoY can obscure longer-term trends and should be complemented with other metrics.

See also: year-over-year, seasonality, quarter-over-quarter (QoQ), month-over-month (MoM), and compound annual growth rate (CAGR).