Abstract
In many plant science experiments, normally there are certain factors that can't be control which may influence the outcome of the work. Such factors include weather and pest pressure. In order to get an accurate and reliable measure of crop performance, the experiment is repeated over time, location or both. These repeated experiments should be analyzed in such a fashion that the data from each individual experiment are combined into one grand analysis. This chapter will cover these types of experiments and their analysis. The influence of nitrogen fertilization on broccoli productivity during two seasons, spring and fall, was used as an example.