Statistical testing
A1
A2
Sign test
Probability: 0.05 significance level (5%), 1% if drugs
Statistical testing determines whether a hypothesis should be accepted or rejected. Tells us whether variables relationships are statistically significant.
Statistical test gives calculated value to compare to critical value in tables
Which critical value?
How do you choose a stat test?
Main hypothesis = alternative hypothesis H1. Other = null hypothesis H0.
What are the tests?
Level of measurement
Repeated measures design
Nominal data/categorical
Looking for a difference not association
Need the signficance level desired
Number of partiicpants/N value
Directional or non-directional test
Ordinal: can order, rate subjectively, no equal intervals, unsfe, converted into ranks when testing e.g. 1st, 2nd
Interval: equal units, safe and parametric, measured and precise, most sophisticated
Nominal: categorical, discrete
One or two tailed
Degree of freedom (rows-1 x columns-1)
Level of significance
Unrelated = independant groups design
Repeated measures and matched pairs are related
Stat test
Mashed (Mann-Whitney)
With (Wilcoxon)
Come (Chi)
Swede (Spearmans rho)
Should (Sign)
Under (Unrelated-T)
Carrots (Chi)
Roast (Related-T)
Potatoes (Pearsons R)
If difference, which experimental design
Level of measurement
Difference or correlation