Chapter 12 Flashcards
What does choosing which statistical analyses and graphs are most appropriate depend on?
each variable’s scale of measurement
What are the levels of a nominal scale? Example?
simply different categories or groups that have no intrinsic numerical properties.
Ex: 2 different kinds of therapies for depression would be nominal categories.
How do variables using an ordinal scale rank order the levels? Ex:
order the levels from lowest to highest, but intervals between each rank order are not equal
A list of the top 10 restaurants in Halifax would use an ordinal scale.
What is an interval scale? Ex?
the distance between each level are equivalent in size.
Ex:
in this case, the difference between 90 and 95 should be the same as the difference between 115 and 1120.
Scores on an intelligence test are an example of an interval scale. However, there is no meaningful zero that represents a total absence of the construct.
What are ratio scales? Ex?
ratio scales have equal intervals in addition to a true zero point.
Ex:
response time and age.
Are the statistical procedures used to analyze data with interval and ratio variables identical? how can they be measured?
yes.
can be summarized using arithmetic average, or what is known as the mean. It is possible to provide a number that reflects the mean amount for these variables.
Is it easy to know precisely whether an ordinal or interval scale is being used in the behavioural sciences? Example?
no.
Ex:
we assume that asking people to rate their state of health on a 4-point scale uses an interval scale, when the points are labelled very good, good, fair, and poor. Yet it is difficult to claim that the difference between very good (4) and good (3) is the same difference between fair (2) and poor (1). However, it is common practice to treat this as an interval scale because when ordinal scales are averaged across many instacnes, they tend to take on properties similar to interval scales.
What are variables measured on interval or ratio scales often referred to as? Why?
continuous variables because the values represent the underlying continuum (at least in theory). Because variables using interval and ratio scales can be treated the same way statistically, we group them together and call them continuous variables.
