The classic criterion for whether you can add to together a set of items to form a scale is an adequate score on coefficient alpha. If all you alphas are above .7 that is indeed adequate. FYI calculating an average score simply involves dividing by a constant (the number of items), so it does not affect the reliability; instead, it just makes the score easier to interpret.

Since this is a relatively straightforward procedure, I am not sure why you are confused. Perhaps you could say something more?

Dear Robbie Lee

A Likert scale is composed of a series of four or more Likert-type items that represent similar questions combined into a single composite score/variable. Likert scale data can be analyzed as interval data, i.e. the mean is the best measure of central tendency. use means and standard deviations to describe the scale.

Best Regards

Dr. Fatemeh Khozaei

Eugene, I believe further clarity is needed wrt your question.

What I have understood is something like this:

There are 5 Likert scale type questions (I will call them statements or items), measuring both confidence and experience for three scenarios. Now, you want to compare the confidence and experience across three scenarios.

Can you tell how many items (questions) are used to measure confidence and experience?

If you have multiple items measuring confidence and experience, check the Cronbach's alpha for those specific groups of items. It means you will have one alpha value for confidence and another for the experience.

Fatemeh Khozaei, in my experience, the Likert scale can consist of less than four items.

I agree with . What do you mean by three scenarios? Do you have three different groups?

Likert's Scale responses from 3 scenarios can be analyse by using mean and standard deviation. Hope I understood your question

The Likert's Scale means are the main criterion for measurement and comparison, between the three scenarios (groups)