# Calculating Cronbach's alpha: Same scale, multiple instances

I'm working on data analysis for my dissertation, and I'm banging my head against the wall when it comes to Cronbach's alpha.

I just completed a pretest; after data cleaning, I have 119 valid and complete responses. These 119 participants answered the same six-item Likert-type scale for nine different scenarios.

However, I am not sure at all how to calculate Cronbach's alpha in this case. Do I calculate alpha for each of the nine scenarios then average them together? Or should I have SPSS calculate new variables, with each of the nine instances of the six items compiled together, and then calculating Cronbach's alpha from that?

...or is there a better calculation altogether?

• Are the six Likert-type items designed to measure the same underlying dimension/construct? What do you mean by 'nine different scenarios'? – Ayalew A. Jan 26 '15 at 7:18
• Good question. The underlying construct relates to perceptions of privacy in specific physical environment, so the same six questions were asked about nine different environments. – Eaners Jan 26 '15 at 7:26
• That means you have 6*9=54 items? – Ayalew A. Jan 26 '15 at 7:40
• Meaning a single item is asked nine times: for environment x, for environment y, etc? – Ayalew A. Jan 26 '15 at 8:58
• Correct--the same six items are asked nine times each. – Eaners Jan 26 '15 at 16:14