Status: Experimental Overview Probability sampling allows OpenTelemetry tracing users to lower span collection costs by the use of randomized sampling techniques. The objectives are: Compatible with the existing W3C trace context sampled flag Spans can be accurately counted using a Span-to-metrics pipeline Traces tend to be complete, even though spans may make independent sampling decisions. This document specifies an approach based on an “r-value” and a “p-value”. At a very high level, r-value is a source of randomness and p-value encodes the sampling probability.