Reply #62: Statistical significance, sample size and signal to nouise ratio [View All]

[GliderGuider]

From the Wikipedia article on statistical significance that has already been discussed in this thread:

http://en.wikipedia.org/wiki/Statistical_significance

Statistical significance can be considered to be the confidence one has in a given result. In a comparison study, it is dependent on the relative difference between the groups compared, the amount of measurement and the noise associated with the measurement. In other words, the confidence one has in a given result being non-random (i.e. it is not a consequence of chance) depends on the signal-to-noise ratio (SNR) and the sample size.

Expressed mathematically, the confidence that a result is not by random chance is given by the following formula by Sackett:

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The model is fine. The reason a longer series gives higher confidence is that the increased number of samples essentially raises the SNR.

You might need to study some basic stats.