South African Journal of Animal Science
Print version ISSN 0375-1589
GOUS, R.M.. Scientific research: the planning process. S. Afr. j. anim. sci. [online]. 2010, vol.40, n.5, pp. 400-406. ISSN 0375-1589.
This paper describes a few important aspects of the process that should be followed before an experiment is conducted. One should start by defining the hypothesis or theory to be tested, which gives a good indication of the way in which the experiment should be designed, and also informs of the way in which the data should be analysed. In order to ensure the success of a trial the number of replications, or animals, should be calculated beforehand, and if too few are possible, or available, then the experimental design should be changed to accommodate this. The approach to the design of response experiments differs from that when two or more independent treatments are being compared, in that fewer replications and more doses would be favoured. Also, it is worth extending the range of inputs beyond the conventionally-applied doses. This is because a response surface must be fitted to the data, and the more points and the wider the range the better for this purpose. Duncan's multiple range test is always inappropriate when analysing a dose/response experiment, and should never be used for this purpose. The optimum dose should be chosen on the basis of the hypothesis being tested, but should preferably include economic data such that an optimum economic dose can be determined, which could be modified as economic circumstances change.
Keywords : Duncan's multiple range test; dose response experiments; interpretation of results; replications.