Making and Analyzing Several Experimental Measurements
This chapter considers the analysis of two sets of multiple variable data in detail. The first data set consists of the weights of 27 rats on each of five occasions, each rat being treated with one of three chemicals (Control for 10 rats, Thyroxin for 7 rats, and Thiouracil for 10 rats). The second data set consists of yields of Cowpea and Maize for 72 plots from an intercropping experiment to examine the effects of different varieties and nitrogen levels on the two crops grown together. In general, the total set of initial information from an experiment will consist of the design information on the structure of experimental units and the treatments applied to the units, together with values for each unit of a number of observed variables. Several measurements characterizing different aspects of the response of the units to the various treatments would be recorded and used together to summarize the effects of the different treatments.