1. Statistical Analysis of Data
Choice & justification of statistical test
Calculation & interpretation of results

2. Statistical Analysis

3. Statistical Analysis

4. Statistical Analysis
Small relationships are detectable between any data sets
They may be caused by chance
They may be caused by something else
Statistical tests help us decide, for any given sets of data, which of these possibilities is more likely

5. Statistical Analysis
If we find that it is highly probable that the relationship was caused by chance, then we assume it was caused by chance
i.e. we accept the null hypothesis
If we find that it is highly improbable that the relationship was caused by chance, then we assume it was caused by something else
i.e. we reject the null hypothesis

6. Minimum Acceptable Probability for Significance
Statistical Analysis
Minimum Acceptable Probability for Significance
Sample Size
P<0.5
P<0.2
P<0.05
P<0.01
P<0.001 5 78 90
102
114
126 6 72 84 7 66 8 60 9 54 10 48 11 42 12 36 13 30 14 24 15 18 16 17