Page 87 - Design for Six Sigma for Service (Six SIGMA Operational Methods)

68 Chapter Four

Likert Scale
The Likert scale (after Rensis Likert) is used for the measurement of attitudes
and opinions. A Likert scale may contain several items such as strongly
agree, agree, neutral, disagree, or strongly disagree. Here is an example:
Netscape is easier to use than Microsoft Internet Explorer.
1. Strongly disagree
2. Disagree
3. Neutral
4. Agree
5. Strongly agree

Sometimes, a numerical scale is explicitly displayed in the questionnaire:
What is your general impression of how the Port city government
affects your business?

Highly Highly
negative positive
1 2 3 4 5
______ ______ ______ ______ ______

Likert items are ordinally scaled. It is not assumed that the difference
between the choices of strongly agree and agree is the same size as the dif-
ference between the choices of agree and neutral. However, in survey data
analysis, it is general practice to treat the Likert scale as an interval scale.
For example, in college course evaluations, there are many Likert scale
questions about a professor’s course teaching; the scores from all students
for each question are averaged as the evaluation score. Clearly this treatment
assumes that the Likert scale is an interval scale.

Open-Ended Questions

Open-ended questions deal with situations where the list of possible
answers is very long or it is very difficult to construct an exhaustive list.
Here are some examples:
What is your favorite place to go for summer vacation? ______
How long have you and your family lived in your current place? ______
What is the first foreign language you learned? ______

Open-ended questions allow respondents to provide longer, more complex
answers than for closed-ended questions. There are several disadvantages to