  The analysis of experiments on measuring neutron lifetime has been made. The
latest most accurate result of measuring neutron lifetime [Phys. Lett. B 605,
72 (2005)] 878.5 \pm 0.8 s differs from the world average value [Phys. Lett. B
667, 1 (2008)] 885.7 \pm 0.8 s by 6.5 standard deviations. In view of this both
the analysis and the Monte Carlo simulation of experiments [Phys. Lett. B 483,
15 (2000)] and [Phys. Rev. Lett. 63, 593 (1989)] have been performed.
Systematic errors about -6 s have been found in both experiments. The table of
results of neutron lifetime measurements is given after corrections and
additions have been made. A new world average value of neutron lifetime makes
up 880.0 \pm 0.9 s. Here is also presented a separate analysis of experiments
on measuring neutron lifetime with UCN and experiments on the beams. The
average neutron lifetime for experiments with UCN is equal to 879.3(0.6) s,
while for experiments on the beams it is equal to 889.1(2.9) s. The present
difference of average values for both groups is (3.3 sigma) and needs
consideration. The contribution of beam experiments into the world average
value is not high, therefore it does not influence the above analysis. However,
it is an independent problem to be solved. It seems desirable that the
precision of beam experiments should be enhanced.
