  The analysis of the noise sources perturbing a test mass (TM) geodesic motion
is the main scientific objective of the LISA Technology Package experiment
(LTP) on board of the LISA Pathfinder space mission. Information on force noise
acting on TMs are obtained with a data reduction procedure involving system
parameters. Such parameters can be estimated from dedicated experimental runs.
Therefore the final estimation of force noise is affected by two sources of
uncertainty. One is statistical and connected to the random nature of noisy
signals. The other is connected to the uncertainties on the system parameters.
The analysis of simulated LTP data is indicating that the major contribution to
the force noise power spectral density uncertainties is coming from the
statistical properties of the spectrum estimator.
