  Network measurement involves an inherent tradeoff between accuracy and
overhead; higher accuracy typically comes at the expense of greater measurement
overhead (measurement frequency, number of probe packets, etc.). Capturing the
"right" balance between these two desiderata - high accuracy and low overhead -
is a key challenge. However, the manner in which accuracy and overhead are
traded off is specific to the measurement method, rendering apples-to-apples
comparisons difficult. To address this, we put forth a novel analytical
framework for quantifying the accuracy-overhead tradeoff for network
measurements. Our framework, inspired by the observer effect in modern physics,
introduces the notion of a network observer factor, which formally captures the
relation between measurement accuracy and overhead. Using our "network observer
framework", measurement methods for the same task can be characterized in terms
of their network observer factors, allowing for apples-to-apples comparisons.
We illustrate the usefulness of our approach by showing how it can be applied
to various application domains and validate its conclusions through
experimental evaluation.
