It was said yesterday that a wavepacket can be considered one wave plus fuzziness. Also, in a wavepacket, a wave is localized. The same mechanism can be used in probability and observation.
It was said yesterday that each experiment is one observation. Each observation is a localized version of the probability wave. So wavepacket is very suitable for observation in probability. It means to observe an outcome in an experiment, the probability wave should be blurred so that it turns into a localized wavepacket so one outcome can be observed.