The role of statistics in psychology
Ciarán Mc Mahon, B.Sc., Ph.D.
Dublin Business School
September 13th 2010
Probably too big a question to handle here, but we can agree that it involves:
- the scientific study of human behaviour, including the mind
This fact leads us to two basic problems in psychology, which statistics can help solve:
1. What do we do with all this information/data?
1. What to do with all this information?
average scores
find patterns
highest scores
lowest scores
most common
make sense
Summarise!
All of these types of activities are what is known as
Descriptive statistics
... these 'describe' the results of our experiments,
making it easier to see what is happening in a large amount of data
2. What does all this information/data mean?
2. What does all this information mean?
understand the data
judgments
comparison of results
probability of the results
validity
reliability
significant differences
Conclusions!
Inferential statistics:
.. these allow us to make calculations which will tell us if the results that we got can be applied to more people than those that we studied
This is important, because we need to know how our results fit into the 'bigger picture' of psychological science
Or in other words, if the results from our sample can be generalised to the population at large
However, both descriptive and inferential statistics are common in many other sciences
Why?
Because in psychology we deal with things like:
ideas
concepts
categories
attitudes
symbols
What do all of these things have in common?
1. They are difficult to measure
2. They are difficult to observe
Two things which science relies on...
In fact, psychology is often accused of being unscientific, because mental phenomena are hard to measure, and hard to observe
But...
If a psychologist can produce good statistics, perhaps demonstrated in a graph...
... then it becomes easier to relate our results to the bigger picture
In effect, statistics is what makes psychology scientific
Without statistics, we cannot
test hypotheses
support theories
disconfirm evidence
or evaluate treatment
The study and use of statistics is, in some ways, much more important in psychology than other sciences
And what will we get from all of these things?
... lots and lots of data!
However, that's not enough...