PYB110 Week One Revision Notes
Two Branches of Statistical Methods
Descriptive is when the information is summarised so that it is more easily understood.
Inferential is used to draw conclusions about regularities in the data.
A variable is something that is able to vary or take different values.
o E.g. across people – gender, height, weight etc. and within people – height, weight,
job satisfaction etc.
Variables are often used within psychology as scores on a particular test, for example.
A value is just a number in a category.
A score is a particular person’s value for that variable.
Kinds of Variables
There are two types of different variables:
Categorical or nominal variables – values which are not numerical and differ in name only.
Numeric or quantitative variables
o Two kinds of numeric variables:
Ordinal or rank-order variables – differ in the order in which the variables
are placed. The intervals are not necessarily equal.
Equal interval variables – equal intervals between ranks are implied. For
example, the difference between a score of 5 and 7 is the same as the
difference between a score of 8 and 10 (2).
Some equal interval variables are measured on what is called a ratio
scale. Equal interval variables are measured on a ratio scale when
they have an absolute zero point. This means that a score of 0 on
the variable indicates a complete absence of the variable.
Equal interval variables also can be classified as discrete or
continuous variables. A discrete variable is one that only has whole
number values (i.e. 2, 6, 919) and a continuous variable can
theoretically have infinite possibilities in between (i.e. 34.789, 6.78,
Shows how frequently each value of a variable occurs. Frequency tables are useful for showing
How to create a frequency table:
Make a list beginning with the lowest score and finishing with the highest. I