@Nobrain,
Assuming you are quoting figures for Standard Deviation, a figure of 1.96 or more indicates that your results lie outside a 95% chance occurence for a normal distribution. In practical terms, you can conclude with a 95% confidence level (or more) that your result is NOT a random one.
The choice of statistical test which yields such SD figures will depend on the nature of your data and your procedure. Each test yields a particular measure like 't' or 'rho' which is assumed to be normally distributed such that SD can be found for it. The assumption of 'normal distribution' is often just that (an assumotion) which can become more reliable the bigger the data set.