  The so-called quantum Zeno effect is essentially a consequence of the
projection postulate for ideal measurements. To test the effect Itano et al.
have performed an experiment on an ensemble of atoms where rapidly repeated
level measurements were realized by means of short laser pulses. Using
dynamical considerations we give an explanation why the projection postulate
can be applied in good approximation to such measurements. Corrections to ideal
measurements are determined explicitly. This is used to discuss in how far the
experiment of Itano et al. can be considered as a test of the quantum Zeno
effect. We also analyze a new possible experiment on a single atom where
stochastic light and dark periods can be interpreted as manifestation of the
quantum Zeno effect. We show that the measurement point of view gives a quick
and intuitive understanding of experiments of the above type, although a finer
analysis has to take the corrections into account.
