Question

In an experiment examining the effects Tai Chi on arthritis pain, Callahan (2010) selected a large sample of individuals with doctor-diagnosed arthritis. Half of the participants immediately began a Tai Chi course and the other half (the control group) waited 8 weeks before beginning. At the end of 8 weeks, the individuals who had experienced Tai Chi had less arthritis pain that those who had not participated in the course. a. Identify the independent variable for this study. b. What scale of measurement is used for the independent variable? c. Identify the dependent variable for this study. d. What scale of measurement is used for the dependent variable?

Answer 1

a) Participants in Tai Chi course

b) Nominal

c) Magnitude of arthritis pain

d) Ordinal

Explanation:

TYPES OF VARIABLES:

• Independent Variable:

An independent variable is the one controlled or changed in an experiment to test the effects on the dependent variable. If this variable is changed, there shall be effects on the experiment.

In this case, number of participants in the course was independent.

• Dependent Variable:

Dependent variable is the one being tested and measured. If the independent variable changes, this variable will show the effect of the changes.

The variables can be determined by their cause and effect on the experiment.

TYPES OF SCALES:

There are two variations in types of scales; Quantitative and Qualitative.

Qualitative variables are measured by either nominal or ordinal scale, while quantitative variables are measured by ratio or interval.

• Nominal scale:

Nominal scales assign identifiers as labels to objects or classes of objects. The assigned numbers carry no additional meaning except as identifiers for example: patient A, patient B etc.

• Ordinal scale:

Ordinal scales assign numbers to objects to rank an attribute. For example: Level of pain 1 - 10, Level of satisfaction etc.

• Interval:

In an interval scale, numbers are assigned to objects such that the interval helps in interpretation of the variables. For example: age of patients: 30 - 40, 40 - 50 etc.

• Ratio:

Ratio scales includes an absolute “zero” point. For example, Rate of arthritis in patients of a particular age etc.