It helps to ensure the validity of results and to make efficient use of time, money and effort. Implementation involves completing all the necessary arrangements for planning the work One of the most difficult parts including everything from finance to permissions. Analysis provides information about each type of data, such as artifacts, ecofacts, etc. Some can be done in the field, but much more is done in the lab.
Interpretation involves a synthesis of all the results of data collection.
Many models, theories and hypotheses are used in this process. Much of this is determined by your theoretical perspective, that is, the way you view the past. Publication involves distributing the results of the work to colleagues and the publics involved. As noted many times already, archaeology does not occur in a social vacuum. Lives are affected in many ways by the things we do.