Cohen, L, Manion, L. and Morrison, J. (2000) Research Methods in Education, 5th edn. London: Routledge Falmer. Chapter 12, pp. 211–25, provides a useful discussion of experimental research.
Greene, J. and D'Oliveira, M. (1982) Learning to Use Statistical Tests in Psychology. Buckingham: Open University Press. Chapter 2, pp. 12–26, discusses experimental designs with one, two or more independent variables, related and unrelated designs and levels of measurement.
Sapsford, R. and Jupp, V. (1996) Data Collection and Analysis. London: Sage.
Pages 12–20 give a shorter but equally useful insight to the problems of undertaking experimental research.
Cohen, K. and Holliday, M. (1996) Practical Statistics for Students. London: Paul Chapman.
Chapter 5, pp. 22–6, provides an easy-to-read overview of the mean, median and mode. Information about how the mean is calculated when the middle score occurs more than once requires a little more effort.
Goulding, S. (1987) in J. Bell Doing Your Research Project. Milton Keynes: Open University Press.