  Precise measurement of frequency sensitivity coefficients (FSCs) of some
physical effects contributing to uncertainty is an important work in type-B
uncertainty (u_B) evaluation of atomic frequency standards. We proposed a
method based on statistical correlation of noise to measure FSCs and evaluate
u_B for atomic frequency standards, and giving a full statistical expression of
FSC as K_I=COV_A(y,x_I)/(sigma(x_I))^2 , where y and x_I are fractional
frequency of atomic frequency standards and noise independent variable of Ith
physical effects, respectively. The confidence value and the effect of time
interval have also been discussed. Except for theoretical derivation, the
method also has been validated by numerical simulation and demonstration
experiments. Comparing with standard method, the statistical correlation of
noise method combines u_B evaluation with type-A uncertainty (u_A), measures
FSCs not by special experiments, but from the monitoring data when the device
is running. It not only gives a criterion to test the standard method, but also
can evaluate many effects at the same time when the device is operating. The
method can be extended to other precision measurement fields and is available
to comprehend the physical effectiveness of the least square method.
