http://www.nottingham.ac.uk/nursing/sonet/rlos/statistics/probability/3.html

Descriptive statistics for interval and ratio scale: includes mean, mode, median, measures of dispersion & standard deviation – with explanation, quizzes & resources:

http://www.nottingham.ac.uk/nursing/sonet/rlos/statistics/descriptive_stats
/index.html

Real datasets & scenario-based learning activities re the analysis of data (Business, Health and Psychology):

http://stars.ac.uk/

Animated resource demonstrating how to convert survey or experimental data into cross tabular data and the steps involved in this process:

http://www.ucel.ac.uk/rlos/cross_tab_data/main.html

For general maths tutorials:

www.mathtutor.ac.uk