Many students are given ready-made problems on which to work but it pays to think carefully before you start a project, whatever stage you are at in your scientific career. Sage advice is given in the book by Cohen and Medley (2000). Here we are concerned with the particular issues that need prior thought in behavioural biology and psychology.

Choosing the level of analysis

Behaviour can be analysed at many different levels, from the complex social interactions within populations to the fine spatial detail of an individual organism's movements. A simple but fundamental point is that the form of measurement used for studying behaviour should reflect the nature of the problem and the questions posed. Conversely, the sorts of phenomena that are uncovered by a behavioural study will inevitably reflect the methods used.

A fine-grained analysis is only appropriate for answering some sorts of question, and a full understanding will not necessarily emerge from describing and analysing behaviour at the most detailed level. While a microscope is an invaluable tool, in some circumstances it would be useless – say, for reading a novel. In other words, the cost of gaining detail can be that higher-level patterns, which may be the most important or relevant features, are lost from view. For example, recording the precise three-dimensional pattern of movements for each limb may be desirable for certain purposes, such as analysing the neurophysiological mechanisms underlying a particular locomotor behaviour pattern.