PYB110 Week Six Revision Notes
Where descriptive statistics are used to describe data, inferential statistics are what we use
to make inferences about the data and make decisions.
The aim of research is to determine the ‘truth’, for example if a theory reflects reality and whether
or not a procedure is really effective. Inferential statistics help us achieve this and do so with the
help of probability. Probability essentially assessed the expected frequency of something and is
based on the likelihood of outcomes.
Probability is symbolised a p.
Probabilities are calculated as the proportion of successful outcomes and can range from 0 –
1. A p = 0 is something that could NEVER happen.
In research it is common to see p < .05 (probability is less than/equal to 5%).
It is very unlikely that events would have a p < .01 (or less than/equal to 1%).
First, we need to identify all possible outcomes and then we need to know how likely it is
that a particular outcome will occur.
However, this formula is only for independent single trials in which each trial does not affect
Example: the probability of landing heads when tossing a coin.
o Number of successful outcome (heads) = 1
o Number of possible outcomes = 2
o Therefore 1 divide by 2 = 0.5.
o Here, the p = .5. T