yoy

YoY, short for year over year, is a method of comparing a statistic for a given period with the same period in the previous year. It is commonly used to assess growth, performance, and trends while reducing the impact of seasonality on monthly or quarterly data. The typical formula for YoY growth is: ((current period value − value in the same period last year) / value in the same period last year) × 100%. The result is expressed as a percentage. For example, if a retailer reports sales of $150 million in November this year and $135 million in November last year, YoY sales growth is ((150−135)/135)×100% ≈ 11.1%.

YoY can be applied to various time frames, including monthly, quarterly, and annual comparisons. Monthly YoY compares the current month to the same month a year earlier, while quarterly YoY compares the current quarter to the same quarter the previous year. It is frequently used in finance, business performance reporting, and economic statistics to illustrate how a metric has changed relative to the prior year.

Applications and interpretation: YoY is used to gauge revenue, earnings, user activity, traffic, or production output. Positive YoY growth indicates improvement relative to the prior year; negative YoY suggests a decline. However, interpretations should consider seasonality, inflation, currency effects, one-time events, and base effects, which can distort percentage changes. Analysts may also use seasonally adjusted figures or compare against moving averages to mitigate these issues.